DELAYED ABSORPTION OF SUBRETINAL FLUID AFTER SCLERAL BUCKLING PROCEDURES: THE SIGNIFICANCE OF SUBRETINAL PRECIPITATES* BY D. M. Robertson, MD INTRODUCTION SURGERY FOR RETINAL DETACHMENT MAY BE ACCOMPANIED BY A
variety of ocular complications.1 These include intraocular hemorrhage,2-4 cystoid macular edema,5 retinal pigment dispersion,6,7 retinal incarceration,2-4 preretinal membrane, 1,8,9 macular pucker, 1,7,1012 massive vitreous retraction1'13'14 (massive periretinal proliferation),15-17 induced refractive errors including irregular astigmatism,18 choroidal detachment, 113'1921 glaucoma, 19'20'22 aseptic uveitis, 19,22,23 exudative retinal detachment,24'25 infection,22'2629 corneal edema,1 anterior segment ischemia,22 central retinal artery occlusion,7 cataracts,121 extraocular muscle imbalance,31 and failure in anatomic reattachment or recurrence of retinal detachment. In instances in which the retinal breaks have otherwise been treated properly, the most common cause for failure in anatomic reattachment is related to massive vitreous retraction1'13'32 (more recently called massive periretinal proliferation).117 This complication is caused by proliferation of metaplastic pigment epithelial cells or glial cells or both. Proliferation of these cells may lead to various stages of organization, from simple preretinal membrane formation to the more extensive massive periretinal proliferation (MPP).15-17'33 It is believed by some that complications encountered during surgical procedures,34 excessive treatment,8 or multiple surgical procedures or any combination of these may be partially * From the Mayo Clinic and Mayo Foundation, Rochester, Minnesota. TR. AM. OPHTH. SoC., vol LXXVI, 1978
558
Robertson
responsible for preretinal membrane formation and MPP.35.36 However, since MPP is generally associated with recurrence of detachment, these eyes probably will be subjected to more surgical procedures than eyes not having this complication if continued efforts are made to reattach the retina. Furthermore, early stages of progressive periretinal proliferation, although difficult to recognize ophthalmoscopically, may cause enough rigidity of the retina to prevent reattachment after surgical procedures that otherwise might be successful. In such cases, additional operations may be related only temporally to the later development of fully expressed massive periretinal proliferation. Nevertheless, excessive treatment or multiple surgical procedures or both may be partially responsible for the development of periretinal proliferation. In retinal surgery, as in any therapeutic discipline, every effort must be made to administer sufficient treatment to reattach the retina while avoiding unnecessary manipulation that might be associated with complications. Accurate judgment in selecting the appropriate type of procedure is necessary to avoid additional surgery. The recent prevalent usage of Custodis-type37 nondrainage procedures has required additional decisional expertise in judging which cases might be amenable to nondrainage techniques and which should be managed more appropriately with release of subretinal fluid.23'32'341 Subsequent to either type of procedure, proper assessment of the absorption of subretinal fluid during the postoperative period is important. Whereas abnormal persistence of subretinal fluid may indicate the presence of small unidentified and untreated holes and the need for additional surgery, in certain circumstances subretinal fluid may persist an uncommonly prolonged time before it is finally totally absorbed. In such circumstances, the retinal breaks may have been adequately treated, but the mechanism for resorbing subretinal fluid may be deficient. In these cases, the clinician may decide prematurely to subject an eye to additional surgical treatment on the assumption that an obscure, untreated hole is responsible for persistent subretinal fluid. Broad areas of the retina then may be treated with additional diathermy or cryopexy, and the buckle may be broadened or converted from a segmental to an encircling element with the hope of adequately treating a suspected but unrecognized break. Such a decision is not only responsible for unnecessary surgery but also may provide additional opportunities for encountering any of the complications already
Subretinal Fluid
559
listed. If the accompaniment of multiple procedures contributes to the development of massive periretinal proliferation, then the risk of development of that complication also becomes significantly increased. It is important therefore that the clinician be familiar with those types of conditions that may be associated with prolonged resorption of subretinal fluid even though treatment has been adequate. Recognizing such cases in advance of the primary surgical approach may influence the physician's choice of treatment, as well as preoperative and postoperative discussions with the patients, and may allow a conservative approach after operation in the face of persistent subretinal fluid. Additional unnecessary surgical treatment can then be avoided. PURPOSE
The purpose of this report is to identify the preoperative clinical characteristics of rhegmatogenous retinal detachments that were associated with delayed subretinal absorption of fluid in a series of 598 consecutive retinal detachments treated with scleral buckling by the author. For this report, delayed subretinal absorption of fluid is defined as "the condition existing when subretinal fluid persists longer than 6 weeks after a surgical procedure for rhegmatogenous retinal detachment, but ultimately absorbs completely with total retinal reattachment." These cases of delayed subretinal absorption of fluid are reviewed in an effort to identify common clinical characteristics that the clinician might be able to recognize before operating. Study of the occurrence of these clinical characteristics in this entire series will provide the clinician with information regarding their relative frequency among patients with retinal detachment. In selected cases, subretinal fluid collected at operation has been examined for protein or cellular characteristics in an effort to provide information that might be helpful in explaining delayed absorption of fluid. Results of these analyses follow. METHODS AND MATERIALS
CLINICAL STUDY
A. Source Material.
The substance of this study is based on a series of 598 consecutive rhegmatogenous retinal detachments that I have managed with scleral buckling from 1970 through 1976. Follow-up for 6 months
560
Robertson
was available for 575 cases, 92 percent of which were utlimately successfully reattached. The clinical analysis is based on these 575 cases. Information has been prospectively collected and recorded in special coded questionnaire forms, which I used over the interval of this study. The coded forms contained questions prepared in such a way that the answers could be easily subjected to computer
analysis. Seven possible entries could be analyzed regarding the interval between operation and total fluid absorption. These were as follows: less than 24 hours, 1 to 2 days, 3 to 5 days, 6 to 13 days, 2 weeks to 6 weeks, 6 weeks to 3 months, and more than 3 months. Those cases in the last two categories were studied separately in an effort to learn if common preoperative, operative, or postoperative factors could be identified that might be associated with prolonged fluid absorption. Examples of two such cases are presented. B. Case Reports. CASE 1
A 67-year-old woman presented with a 2-week history of visual blurring in the left eye. Visual acuity was 20/20 in the right eye and finger counting in the left eye. A detachment containing a single horseshoe tear was present in the superior temporal quadrant of the left eye. The detachment was not unusual, except for the presence of numerous small cream-colored lesions located on the undersurface of the detached retina (Figure 1 A and B). These lesions are similar in appearance to mutton-fat keratic precipitates. Since their location is on the undersurface of the detached retina, I refer to them as "subretinal precipitates." The detachment was treated with a segmental buckling procedure using cryopexy and an episcleral sponge without release of subretinal fluid. Within 3 days after the operation the subretinal fluid seemed to have absorbed from the posterior pole. However, 1 month later the distribution of the subretinal fluid had changed little if at all (Figure 1 C). In order to eliminate the possibility that fluid was leaking through the treated tear or through another unrecognized, untreated break, the buckle was revised using a second nondrainage surgical procedure to make it broader and higher. Four months after the second surgical procedure, subretinal fluid was still present. However, when the patient returned, 11 months after the second operation, the retina was totally attached, and the visual acuity had recovered to 20/30. Comment. Since subretinal fluid persisted for months after the second surgical procedure, I concluded that revision of the buckle probably had been unnecessary. Nevertheless, this case served to make me curious about the significance of subretinal precipitates.
Subretinal Fluid
561
A
.:..:
...
FIGURE 1
A: Drawing of retinal detachment demonstrating single small horseshoe tear and relative distribution of subretinal precipitates. B: Clinical photograph of retina of same patient showing numerous dotlike subretinal precipitates. C: Drawing of persistent retinal detachment 1 month after segmental episcleral buckling procedure. Subretinal precipitates remain under the peripheral detachment. CASE 2
A 62-year-old man experienced symptoms of floaters in the right eye for 2 to 3 months before presenting with a two-quadrant detachment involving the macula which reduced visual acuity to 20/60. Two small horseshoe tears were responsible for the detachment. Numerous subretinal precipitates were observed. Scleral buckling was performed utilizing cryopexy, two radially oriented episcleral sponges, and release of subretinal fluid through a sclerotomy. Two days later a considerable amount of subretinal fluid persisted under the more peripheral portion of the retina, but the
562
Robertson
FIGURE 2
A: Example of retinal detachment with moderate number of subretinal precipitates. B: Example of retinal detachment with many subretinal precipitates.
563
Subretinal Fluid
subretinal fluid had disappeared at the posterior pole of the eye. Six weeks after the operation, the detachment appeared unchanged and subretinal precipitates were still visible. Since I was unable to find a definite retinal break responsible for the persistence of the subretinal fluid, observation seemed justified. Six months after the operation, all subretinal fluid had resorbed, and the visual acuity had recovered to 20/25. Comment. After seeing additional rhegmatogenous detachments with subretinal precipitates, I soon formed the distinct clinical impression that if subretinal precipitates could be easily recognized by indirect ophthalmoscopy before operation, a delay in absorption of subretinal fluid could be anticipated after scleral buckling irrespective of partial drainage of the subretinal fluid. However, since clinical impressions are often in error, it seemed appropriate to study the subject of delayed absorption of fluid in a more structured way.
C. Additional Analysis. A second condition that seemed important to analyze in this study
related to the presence or absence of subretinal precipitates in the preoperative state. Three possible entries could be analyzed from the established code with respect to subretinal precipitates. There could be none, few (Figure 2 A), or many (Figure 2 B). The cases recognized to have subretinal precipitates were studied to determine the relationship between subretinal precipitates and a delay in absorption of subretinal fluid after scleral buckling. D. Results. 1. Subretinal Fluid Absorption Delayed 3 Months or Longer.
In 19 cases subretinal fluid remained 3 months or more before ultimately absorbing (Table I). In 9 of these 19 cases, the presence of subretinal precipitates was identified on preoperative examination. In 7 of the remaining 10 cases, the detachments were caused by small round peripheral atrophic holes without opercula or evidence of vitreous reaction. An additional case had a long-standing inferior dialysis and another was complicated TABLE I. ABSORPTION OF SUBREIINAL FLUID DELAYED BEYOND 3 MONTHS (19 PATIENTS)
Characteristics of retinal detachments Subretinal precipitates Small round atrophic holes Inferior dialysis Complicated case
Number of patients 9 7 1 2
564
Robertson due to five previous operations, including an unsuccessful attempt to repair retinal detachment. In the final case, the patient had had previous trauma to the eye with intraocular hemorrhage and had undergone an unsuccessful attempt to repair the retina 1 month earlier at another institution. In 15 of these 19 cases, subretinal fluid was released through a sclerotomy, although no special effort was made to drain all of the subretinal fluid. In none of the 19 cases did I recognize appreciable, postoperative accumulation of subretinal fluid over the amount remaining in the eye on completion of the operation. Most of the nine cases with preoperative subretinal precipitates were considered to have fresh detachments, that is, detachments of recent onset. For example, in six of the nine cases, the duration of the detachment was estimated to be between 5 days and 3 weeks. In three of the nine cases the detachments did have demarcation lines, however, indicating that some were of long duration, since the formation of these lines generally takes at least 2 to 3 months. Two of the nine detachments were caused by small round peripheral holes, whereas the others were caused by horseshoe tears. In seven of the nine cases subretinal fluid was drained at the time of operation. In contrast to the detachments associated with subretinal precipitates, the seven cases associated with small round atrophic holes without subretinal precipitates were distinctive in that the detachments were generally long standing. In five of the seven cases, for example, demarcation lines were observed. Interestingly, in only two of these seven cases did the detachment involve the macula. In six of the seven detachments, subretinal fluid was drained, and in three of the seven cases, lattice degeneration was noted. A schematic representation of this group of detachments caused by round peripheral atrophic holes is shown in Figure 3.
2. Subretinal Fluid Absorption Delayed 6 Weeks or Longer. When a collective analysis was made of all those cases in which subretinal fluid persisted longer than 6 weeks, including those with fluid persisting longer than 3 months, there was a broader variety of retinal detachment types (Table II). Of the 39 cases in this entire group, 17 (44 percent) had subretinal precipitates; in 14, the subretinal fluid was drained. Eleven additional cases without subretinal precipitates were associated with peripheral
Subretinal Fluid
565
FIGURE 3
Drawing of retinal detachment caused by round peripheral atrophic hole. Note the pigmented demarcation lines.
atrophic round holes (six had demarcation lines and six had lattice degeneration). In 3 of the 39 cases, exudative detachment developed after treatment, and in 1 of the 3 it was associated with an infected explant. Two cases had long-standing retinal detachments: one with an inferior dialysis (already mentioned), and the other had had two unsuccessful retinal operations 9 years earlier. One had a moderately severe subretinal hemorrhage that occurred with release of subretinal fluid, and two had evidence of considerable vitreous traction. Two additional cases were complicated by a history of previous multiple surgical procedures, which, in one instance, involved a recent operation on the anterior segment with anterior vitrectomy. In this case a definite break could not be recognized. In the remaining case, post-traumatic intraocular hemorrhage had developed previous-
Robertson
566
TABLE II. ABSORPTION OF SUBRETINAL FLUID DELAYED MORE THAN 6 WEEKS (39 PATIENTS)
Characteristics of retinal detachment Subretinal precipitates Small round atrophic hole Exudative detachment Other long-standing detachments Subretinal hemorrhage Complicated case Vitreous changes
Number of patients 17 11 3 2 1 3 2
ly, and an attempt to repair the retina elsewhere had been unsuccessful. Efforts to relate delayed absorption of fluid to the age of the patient, size of the largest break, number of cryopexy lesions, number of quadrants involved in the detached retina, presence or absence of aphakia, and presence or absence of uveitis were negative. An analysis of the final visual acuities in these 39 patients indicated that the distribution of the final visual acuities in the patients with delayed absorption of fluid was not significantly different from the distribution of acuities in the overall series. 3. Frequency of Subretinal Precipitates. Of the 575 cases, 69 (12 percent) were recognized as having subretinal precipitates (Table III). Among these 69 cases, 17 (25 percent) were associated with a delay in complete absorption of subretinal fluid for an interval of more than 6 weeks. LABORATORY STUDY
A. Methods of Collection and Analysis of Subretinal Fluid Studies were conducted on subretinal fluid collected from 43 cases. TABLE III. RELATIONSHIP OF SUBRETINAL PRECIPITATES TO DELAYED ABSORPTION OF SUBRETINAL FLUID
Incidence In 575 patients In patients with fluid absorption delayed 6 weeks Statistical significance of relationship of precipitates to delayed fluid absorption as determined by chi-square test
69/575 (12%) 17/39 (44%)
P
variety of ocular complications.1 These include intraocular hemorrhage,2-4 cystoid macular edema,5 retinal pigment dispersion,6,7 retinal incarceration,2-4 preretinal membrane, 1,8,9 macular pucker, 1,7,1012 massive vitreous retraction1'13'14 (massive periretinal proliferation),15-17 induced refractive errors including irregular astigmatism,18 choroidal detachment, 113'1921 glaucoma, 19'20'22 aseptic uveitis, 19,22,23 exudative retinal detachment,24'25 infection,22'2629 corneal edema,1 anterior segment ischemia,22 central retinal artery occlusion,7 cataracts,121 extraocular muscle imbalance,31 and failure in anatomic reattachment or recurrence of retinal detachment. In instances in which the retinal breaks have otherwise been treated properly, the most common cause for failure in anatomic reattachment is related to massive vitreous retraction1'13'32 (more recently called massive periretinal proliferation).117 This complication is caused by proliferation of metaplastic pigment epithelial cells or glial cells or both. Proliferation of these cells may lead to various stages of organization, from simple preretinal membrane formation to the more extensive massive periretinal proliferation (MPP).15-17'33 It is believed by some that complications encountered during surgical procedures,34 excessive treatment,8 or multiple surgical procedures or any combination of these may be partially * From the Mayo Clinic and Mayo Foundation, Rochester, Minnesota. TR. AM. OPHTH. SoC., vol LXXVI, 1978
558
Robertson
responsible for preretinal membrane formation and MPP.35.36 However, since MPP is generally associated with recurrence of detachment, these eyes probably will be subjected to more surgical procedures than eyes not having this complication if continued efforts are made to reattach the retina. Furthermore, early stages of progressive periretinal proliferation, although difficult to recognize ophthalmoscopically, may cause enough rigidity of the retina to prevent reattachment after surgical procedures that otherwise might be successful. In such cases, additional operations may be related only temporally to the later development of fully expressed massive periretinal proliferation. Nevertheless, excessive treatment or multiple surgical procedures or both may be partially responsible for the development of periretinal proliferation. In retinal surgery, as in any therapeutic discipline, every effort must be made to administer sufficient treatment to reattach the retina while avoiding unnecessary manipulation that might be associated with complications. Accurate judgment in selecting the appropriate type of procedure is necessary to avoid additional surgery. The recent prevalent usage of Custodis-type37 nondrainage procedures has required additional decisional expertise in judging which cases might be amenable to nondrainage techniques and which should be managed more appropriately with release of subretinal fluid.23'32'341 Subsequent to either type of procedure, proper assessment of the absorption of subretinal fluid during the postoperative period is important. Whereas abnormal persistence of subretinal fluid may indicate the presence of small unidentified and untreated holes and the need for additional surgery, in certain circumstances subretinal fluid may persist an uncommonly prolonged time before it is finally totally absorbed. In such circumstances, the retinal breaks may have been adequately treated, but the mechanism for resorbing subretinal fluid may be deficient. In these cases, the clinician may decide prematurely to subject an eye to additional surgical treatment on the assumption that an obscure, untreated hole is responsible for persistent subretinal fluid. Broad areas of the retina then may be treated with additional diathermy or cryopexy, and the buckle may be broadened or converted from a segmental to an encircling element with the hope of adequately treating a suspected but unrecognized break. Such a decision is not only responsible for unnecessary surgery but also may provide additional opportunities for encountering any of the complications already
Subretinal Fluid
559
listed. If the accompaniment of multiple procedures contributes to the development of massive periretinal proliferation, then the risk of development of that complication also becomes significantly increased. It is important therefore that the clinician be familiar with those types of conditions that may be associated with prolonged resorption of subretinal fluid even though treatment has been adequate. Recognizing such cases in advance of the primary surgical approach may influence the physician's choice of treatment, as well as preoperative and postoperative discussions with the patients, and may allow a conservative approach after operation in the face of persistent subretinal fluid. Additional unnecessary surgical treatment can then be avoided. PURPOSE
The purpose of this report is to identify the preoperative clinical characteristics of rhegmatogenous retinal detachments that were associated with delayed subretinal absorption of fluid in a series of 598 consecutive retinal detachments treated with scleral buckling by the author. For this report, delayed subretinal absorption of fluid is defined as "the condition existing when subretinal fluid persists longer than 6 weeks after a surgical procedure for rhegmatogenous retinal detachment, but ultimately absorbs completely with total retinal reattachment." These cases of delayed subretinal absorption of fluid are reviewed in an effort to identify common clinical characteristics that the clinician might be able to recognize before operating. Study of the occurrence of these clinical characteristics in this entire series will provide the clinician with information regarding their relative frequency among patients with retinal detachment. In selected cases, subretinal fluid collected at operation has been examined for protein or cellular characteristics in an effort to provide information that might be helpful in explaining delayed absorption of fluid. Results of these analyses follow. METHODS AND MATERIALS
CLINICAL STUDY
A. Source Material.
The substance of this study is based on a series of 598 consecutive rhegmatogenous retinal detachments that I have managed with scleral buckling from 1970 through 1976. Follow-up for 6 months
560
Robertson
was available for 575 cases, 92 percent of which were utlimately successfully reattached. The clinical analysis is based on these 575 cases. Information has been prospectively collected and recorded in special coded questionnaire forms, which I used over the interval of this study. The coded forms contained questions prepared in such a way that the answers could be easily subjected to computer
analysis. Seven possible entries could be analyzed regarding the interval between operation and total fluid absorption. These were as follows: less than 24 hours, 1 to 2 days, 3 to 5 days, 6 to 13 days, 2 weeks to 6 weeks, 6 weeks to 3 months, and more than 3 months. Those cases in the last two categories were studied separately in an effort to learn if common preoperative, operative, or postoperative factors could be identified that might be associated with prolonged fluid absorption. Examples of two such cases are presented. B. Case Reports. CASE 1
A 67-year-old woman presented with a 2-week history of visual blurring in the left eye. Visual acuity was 20/20 in the right eye and finger counting in the left eye. A detachment containing a single horseshoe tear was present in the superior temporal quadrant of the left eye. The detachment was not unusual, except for the presence of numerous small cream-colored lesions located on the undersurface of the detached retina (Figure 1 A and B). These lesions are similar in appearance to mutton-fat keratic precipitates. Since their location is on the undersurface of the detached retina, I refer to them as "subretinal precipitates." The detachment was treated with a segmental buckling procedure using cryopexy and an episcleral sponge without release of subretinal fluid. Within 3 days after the operation the subretinal fluid seemed to have absorbed from the posterior pole. However, 1 month later the distribution of the subretinal fluid had changed little if at all (Figure 1 C). In order to eliminate the possibility that fluid was leaking through the treated tear or through another unrecognized, untreated break, the buckle was revised using a second nondrainage surgical procedure to make it broader and higher. Four months after the second surgical procedure, subretinal fluid was still present. However, when the patient returned, 11 months after the second operation, the retina was totally attached, and the visual acuity had recovered to 20/30. Comment. Since subretinal fluid persisted for months after the second surgical procedure, I concluded that revision of the buckle probably had been unnecessary. Nevertheless, this case served to make me curious about the significance of subretinal precipitates.
Subretinal Fluid
561
A
.:..:
...
FIGURE 1
A: Drawing of retinal detachment demonstrating single small horseshoe tear and relative distribution of subretinal precipitates. B: Clinical photograph of retina of same patient showing numerous dotlike subretinal precipitates. C: Drawing of persistent retinal detachment 1 month after segmental episcleral buckling procedure. Subretinal precipitates remain under the peripheral detachment. CASE 2
A 62-year-old man experienced symptoms of floaters in the right eye for 2 to 3 months before presenting with a two-quadrant detachment involving the macula which reduced visual acuity to 20/60. Two small horseshoe tears were responsible for the detachment. Numerous subretinal precipitates were observed. Scleral buckling was performed utilizing cryopexy, two radially oriented episcleral sponges, and release of subretinal fluid through a sclerotomy. Two days later a considerable amount of subretinal fluid persisted under the more peripheral portion of the retina, but the
562
Robertson
FIGURE 2
A: Example of retinal detachment with moderate number of subretinal precipitates. B: Example of retinal detachment with many subretinal precipitates.
563
Subretinal Fluid
subretinal fluid had disappeared at the posterior pole of the eye. Six weeks after the operation, the detachment appeared unchanged and subretinal precipitates were still visible. Since I was unable to find a definite retinal break responsible for the persistence of the subretinal fluid, observation seemed justified. Six months after the operation, all subretinal fluid had resorbed, and the visual acuity had recovered to 20/25. Comment. After seeing additional rhegmatogenous detachments with subretinal precipitates, I soon formed the distinct clinical impression that if subretinal precipitates could be easily recognized by indirect ophthalmoscopy before operation, a delay in absorption of subretinal fluid could be anticipated after scleral buckling irrespective of partial drainage of the subretinal fluid. However, since clinical impressions are often in error, it seemed appropriate to study the subject of delayed absorption of fluid in a more structured way.
C. Additional Analysis. A second condition that seemed important to analyze in this study
related to the presence or absence of subretinal precipitates in the preoperative state. Three possible entries could be analyzed from the established code with respect to subretinal precipitates. There could be none, few (Figure 2 A), or many (Figure 2 B). The cases recognized to have subretinal precipitates were studied to determine the relationship between subretinal precipitates and a delay in absorption of subretinal fluid after scleral buckling. D. Results. 1. Subretinal Fluid Absorption Delayed 3 Months or Longer.
In 19 cases subretinal fluid remained 3 months or more before ultimately absorbing (Table I). In 9 of these 19 cases, the presence of subretinal precipitates was identified on preoperative examination. In 7 of the remaining 10 cases, the detachments were caused by small round peripheral atrophic holes without opercula or evidence of vitreous reaction. An additional case had a long-standing inferior dialysis and another was complicated TABLE I. ABSORPTION OF SUBREIINAL FLUID DELAYED BEYOND 3 MONTHS (19 PATIENTS)
Characteristics of retinal detachments Subretinal precipitates Small round atrophic holes Inferior dialysis Complicated case
Number of patients 9 7 1 2
564
Robertson due to five previous operations, including an unsuccessful attempt to repair retinal detachment. In the final case, the patient had had previous trauma to the eye with intraocular hemorrhage and had undergone an unsuccessful attempt to repair the retina 1 month earlier at another institution. In 15 of these 19 cases, subretinal fluid was released through a sclerotomy, although no special effort was made to drain all of the subretinal fluid. In none of the 19 cases did I recognize appreciable, postoperative accumulation of subretinal fluid over the amount remaining in the eye on completion of the operation. Most of the nine cases with preoperative subretinal precipitates were considered to have fresh detachments, that is, detachments of recent onset. For example, in six of the nine cases, the duration of the detachment was estimated to be between 5 days and 3 weeks. In three of the nine cases the detachments did have demarcation lines, however, indicating that some were of long duration, since the formation of these lines generally takes at least 2 to 3 months. Two of the nine detachments were caused by small round peripheral holes, whereas the others were caused by horseshoe tears. In seven of the nine cases subretinal fluid was drained at the time of operation. In contrast to the detachments associated with subretinal precipitates, the seven cases associated with small round atrophic holes without subretinal precipitates were distinctive in that the detachments were generally long standing. In five of the seven cases, for example, demarcation lines were observed. Interestingly, in only two of these seven cases did the detachment involve the macula. In six of the seven detachments, subretinal fluid was drained, and in three of the seven cases, lattice degeneration was noted. A schematic representation of this group of detachments caused by round peripheral atrophic holes is shown in Figure 3.
2. Subretinal Fluid Absorption Delayed 6 Weeks or Longer. When a collective analysis was made of all those cases in which subretinal fluid persisted longer than 6 weeks, including those with fluid persisting longer than 3 months, there was a broader variety of retinal detachment types (Table II). Of the 39 cases in this entire group, 17 (44 percent) had subretinal precipitates; in 14, the subretinal fluid was drained. Eleven additional cases without subretinal precipitates were associated with peripheral
Subretinal Fluid
565
FIGURE 3
Drawing of retinal detachment caused by round peripheral atrophic hole. Note the pigmented demarcation lines.
atrophic round holes (six had demarcation lines and six had lattice degeneration). In 3 of the 39 cases, exudative detachment developed after treatment, and in 1 of the 3 it was associated with an infected explant. Two cases had long-standing retinal detachments: one with an inferior dialysis (already mentioned), and the other had had two unsuccessful retinal operations 9 years earlier. One had a moderately severe subretinal hemorrhage that occurred with release of subretinal fluid, and two had evidence of considerable vitreous traction. Two additional cases were complicated by a history of previous multiple surgical procedures, which, in one instance, involved a recent operation on the anterior segment with anterior vitrectomy. In this case a definite break could not be recognized. In the remaining case, post-traumatic intraocular hemorrhage had developed previous-
Robertson
566
TABLE II. ABSORPTION OF SUBRETINAL FLUID DELAYED MORE THAN 6 WEEKS (39 PATIENTS)
Characteristics of retinal detachment Subretinal precipitates Small round atrophic hole Exudative detachment Other long-standing detachments Subretinal hemorrhage Complicated case Vitreous changes
Number of patients 17 11 3 2 1 3 2
ly, and an attempt to repair the retina elsewhere had been unsuccessful. Efforts to relate delayed absorption of fluid to the age of the patient, size of the largest break, number of cryopexy lesions, number of quadrants involved in the detached retina, presence or absence of aphakia, and presence or absence of uveitis were negative. An analysis of the final visual acuities in these 39 patients indicated that the distribution of the final visual acuities in the patients with delayed absorption of fluid was not significantly different from the distribution of acuities in the overall series. 3. Frequency of Subretinal Precipitates. Of the 575 cases, 69 (12 percent) were recognized as having subretinal precipitates (Table III). Among these 69 cases, 17 (25 percent) were associated with a delay in complete absorption of subretinal fluid for an interval of more than 6 weeks. LABORATORY STUDY
A. Methods of Collection and Analysis of Subretinal Fluid Studies were conducted on subretinal fluid collected from 43 cases. TABLE III. RELATIONSHIP OF SUBRETINAL PRECIPITATES TO DELAYED ABSORPTION OF SUBRETINAL FLUID
Incidence In 575 patients In patients with fluid absorption delayed 6 weeks Statistical significance of relationship of precipitates to delayed fluid absorption as determined by chi-square test
69/575 (12%) 17/39 (44%)
P
