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Clinical science
Lateral incomitancy and surgical results in intermittent exotropia Chang Ho Yoon, Seong-Joon Kim Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea Correspondence to Dr Seong-Joon Kim, Department of Ophthalmology, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea; [email protected] Received 20 February 2014 Revised 14 April 2014 Accepted 26 April 2014 Published Online First 15 May 2014
ABSTRACT Aim To evaluate the prevalence of lateral incomitance (LI) and its association with surgical outcome in intermittent exotropia. Methods We retrospectively surveyed patients who had been followed up for 18 months or more after surgery for intermittent exotropia conducted from 1 September 2008 to 31 December 2010. Preoperative significant LI ( preLI+) was defined as a decrease of >5 prism dioptres (PD) in exodeviation of distant gaze at lateral gaze. Postoperative significant LI ( postLI+) was defined as a difference of >5 PD between distant and lateral gaze. Gender, age at surgery, binocular spherical equivalent, preoperative angle of deviation, type of intermittent exotropia, type of surgery, and stereopsis were investigated together with associations with LI and surgical results. Surgical results were analysed using data from a postoperative period of at least 18 months. Results Of 155 patients, 63 (40.6%) had preLI+. Surgical failure including consecutive esotropia was not associated with preLI+ ( p=0.140). In subgroup analysis, bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession (ULR) procedures did not induce significant LI, but non-operated eyes with ULR showed reduced LI after surgery. Conclusions Surgical outcomes in ULR and BLR for intermittent exotropia correction showed no association with preLI+. The prevalences of significant LI were unchanged after surgery in both groups.
INTRODUCTION
To cite: Yoon CH, Kim S-J. Br J Ophthalmol 2014;98:1404–1408. 1404
Lateral incomitance (LI) is defined as decreased exodeviation in right or left lateral gaze compared with the primary position.1 While the mechanism of LI is obscure, pulley instability, impaired vergence facility, superior oblique palsy, mechanical limitation, and changes in muscle fibre type and distribution are considered possible causes.2–5 The clinical implications of LI are controversial. Although it has been reported that preoperative significant LI ( preLI+) is associated with surgical overcorrection in intermittent exotropia,1 6 some authors have suggested that preLI+ does not influence the surgical results.4 7 A significant degree of unilateral lateral rectus recession (ULR) is a potent risk for postoperative significant LI ( postLI+), but there are few studies about change of LI after surgery.8–10 There are limited studies on associated factors and prevalence of LI, and this is the first study involving statistical analysis of preoperative and postoperative LI and associated factors in intermittent exotropia. This study aimed to investigate influencing factors in preoperative and
postoperative LI and to determine whether LI affects surgical outcome in intermittent exotropia.
METHODS This study was approved by our institutional review and aethical board (No. H-1306-082-498). The study protocol followed the tenets of the Declaration of Helsinki. Patients who underwent either the bilateral lateral rectus recession (BLR) or ULR for treatment of intermittent exotropia from 1 September 2008 to 31 December 2010 were enrolled. The minimum required follow-up period after surgery was 18 months. However, patients who required reoperation within 18 months after the primary surgery were included and only the patient data before reoperation were used for analysis. Ocular examination included measurement of uncorrected and best corrected visual acuities with all refractions performed under cycloplegia. Preoperatively, deviation was measured using the alternate prism and cover test at distance (6 m) and near (33 cm) in primary and lateral gaze, with appropriate spectacle correction when required. A base in prism was placed over the adducting eye in measurements of lateral gaze deviations. The minimum required vertical and/or oblique muscle surgery, or vertical transposition of horizontal muscles during intermittent exotropia surgery, or other ocular abnormalities were excluded. Patients were also excluded if they had paralytic or restrictive exotropia, duction and version abnormalities, trauma history including orbital wall fracture, amblyopia, or other systemic abnormalities including mental retardation and cerebral palsy. Amblyopia was defined as a difference of two or more lines in Snellen visual acuity charts between the best corrected visual acuity of each eye. Patients who had recovered from amblyopia before surgery were included. All surgeries were performed by a single surgeon (S-JK) using the surgical formula according to the Park’s method.11 Surgical dosage was based on the angle of distant deviation. BLR was performed in patients with exodeviation of 20 prism dioptres (PD) or more. ULR was performed in patients with exodeviation of 25 PD or less. It is known that the surgical results of ULR and BLR in mild to moderate intermittent exotropia are equally effective.10 12 The selection of surgical procedure in patients with 20–25 PD exodeviation was made by the operating surgeon, who had no preference for BLR or ULR. PreLI+ was defined as a decrease of more than 5 PD in preoperative exodeviation at distance at right or left gaze. PostLI+ was defined as a difference of
Yoon CH, et al. Br J Ophthalmol 2014;98:1404–1408. doi:10.1136/bjophthalmol-2014-305132
Downloaded from http://bjo.bmj.com/ on June 13, 2015 - Published by group.bmj.com
Clinical science more than 5 PD in postoperative deviation at distance compared with right or left gaze. All patients received follow-up examinations at 1 week, 1 month, 3 or 6 months, and approximate 6-month intervals after the operation. Surgical success was defined as esophoria/ tropia of
Clinical science
Lateral incomitancy and surgical results in intermittent exotropia Chang Ho Yoon, Seong-Joon Kim Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Republic of Korea Correspondence to Dr Seong-Joon Kim, Department of Ophthalmology, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea; [email protected] Received 20 February 2014 Revised 14 April 2014 Accepted 26 April 2014 Published Online First 15 May 2014
ABSTRACT Aim To evaluate the prevalence of lateral incomitance (LI) and its association with surgical outcome in intermittent exotropia. Methods We retrospectively surveyed patients who had been followed up for 18 months or more after surgery for intermittent exotropia conducted from 1 September 2008 to 31 December 2010. Preoperative significant LI ( preLI+) was defined as a decrease of >5 prism dioptres (PD) in exodeviation of distant gaze at lateral gaze. Postoperative significant LI ( postLI+) was defined as a difference of >5 PD between distant and lateral gaze. Gender, age at surgery, binocular spherical equivalent, preoperative angle of deviation, type of intermittent exotropia, type of surgery, and stereopsis were investigated together with associations with LI and surgical results. Surgical results were analysed using data from a postoperative period of at least 18 months. Results Of 155 patients, 63 (40.6%) had preLI+. Surgical failure including consecutive esotropia was not associated with preLI+ ( p=0.140). In subgroup analysis, bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession (ULR) procedures did not induce significant LI, but non-operated eyes with ULR showed reduced LI after surgery. Conclusions Surgical outcomes in ULR and BLR for intermittent exotropia correction showed no association with preLI+. The prevalences of significant LI were unchanged after surgery in both groups.
INTRODUCTION
To cite: Yoon CH, Kim S-J. Br J Ophthalmol 2014;98:1404–1408. 1404
Lateral incomitance (LI) is defined as decreased exodeviation in right or left lateral gaze compared with the primary position.1 While the mechanism of LI is obscure, pulley instability, impaired vergence facility, superior oblique palsy, mechanical limitation, and changes in muscle fibre type and distribution are considered possible causes.2–5 The clinical implications of LI are controversial. Although it has been reported that preoperative significant LI ( preLI+) is associated with surgical overcorrection in intermittent exotropia,1 6 some authors have suggested that preLI+ does not influence the surgical results.4 7 A significant degree of unilateral lateral rectus recession (ULR) is a potent risk for postoperative significant LI ( postLI+), but there are few studies about change of LI after surgery.8–10 There are limited studies on associated factors and prevalence of LI, and this is the first study involving statistical analysis of preoperative and postoperative LI and associated factors in intermittent exotropia. This study aimed to investigate influencing factors in preoperative and
postoperative LI and to determine whether LI affects surgical outcome in intermittent exotropia.
METHODS This study was approved by our institutional review and aethical board (No. H-1306-082-498). The study protocol followed the tenets of the Declaration of Helsinki. Patients who underwent either the bilateral lateral rectus recession (BLR) or ULR for treatment of intermittent exotropia from 1 September 2008 to 31 December 2010 were enrolled. The minimum required follow-up period after surgery was 18 months. However, patients who required reoperation within 18 months after the primary surgery were included and only the patient data before reoperation were used for analysis. Ocular examination included measurement of uncorrected and best corrected visual acuities with all refractions performed under cycloplegia. Preoperatively, deviation was measured using the alternate prism and cover test at distance (6 m) and near (33 cm) in primary and lateral gaze, with appropriate spectacle correction when required. A base in prism was placed over the adducting eye in measurements of lateral gaze deviations. The minimum required vertical and/or oblique muscle surgery, or vertical transposition of horizontal muscles during intermittent exotropia surgery, or other ocular abnormalities were excluded. Patients were also excluded if they had paralytic or restrictive exotropia, duction and version abnormalities, trauma history including orbital wall fracture, amblyopia, or other systemic abnormalities including mental retardation and cerebral palsy. Amblyopia was defined as a difference of two or more lines in Snellen visual acuity charts between the best corrected visual acuity of each eye. Patients who had recovered from amblyopia before surgery were included. All surgeries were performed by a single surgeon (S-JK) using the surgical formula according to the Park’s method.11 Surgical dosage was based on the angle of distant deviation. BLR was performed in patients with exodeviation of 20 prism dioptres (PD) or more. ULR was performed in patients with exodeviation of 25 PD or less. It is known that the surgical results of ULR and BLR in mild to moderate intermittent exotropia are equally effective.10 12 The selection of surgical procedure in patients with 20–25 PD exodeviation was made by the operating surgeon, who had no preference for BLR or ULR. PreLI+ was defined as a decrease of more than 5 PD in preoperative exodeviation at distance at right or left gaze. PostLI+ was defined as a difference of
Yoon CH, et al. Br J Ophthalmol 2014;98:1404–1408. doi:10.1136/bjophthalmol-2014-305132
Downloaded from http://bjo.bmj.com/ on June 13, 2015 - Published by group.bmj.com
Clinical science more than 5 PD in postoperative deviation at distance compared with right or left gaze. All patients received follow-up examinations at 1 week, 1 month, 3 or 6 months, and approximate 6-month intervals after the operation. Surgical success was defined as esophoria/ tropia of
