Graefes Arch Clin Exp Ophthalmol DOI 10.1007/s00417-013-2517-y
RETINAL DISORDERS
Usability of a gravity- and tilt-compensated sensor with data logging function to measure posturing compliance in patients after macular hole surgery: a pilot study Martin Alexander Leitritz & Focke Ziemssen & Bogomil Voykov & Karl Ulrich Bartz-Schmidt
Received: 5 September 2013 / Revised: 25 October 2013 / Accepted: 28 October 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Background To investigate the use of a small gravity- and tiltcompensated, head-fixed sensor with data-logging function to measure compliance and head posture of patients after macular hole surgery based on the recommendation of a face-down position. Main outcome measures were the median inclination, the times with correct or incorrect head position and the acceptance/annoyance of a data-logging device. Methods A small battery-driven electronic sensor device with gravity and tilt compensations was placed within a plastic box and fixed on a patient’s head with a headband. Face-down position data were logged every half second for 24 h after macular hole surgery and were stored on a memory card. Results Thirteen patients were involved (seven females, six males, median age, 68 years, range, 50–75 years), two cases with early dropout. Ten of 11 datasets could be evaluated showing a complete data record file. The average percentage for face-down >45° was 18 % within 24 h and 17 % in the daytime. The median inclination was −6.7° (min: −89.7° max: 90°). The sensor system was well tolerated and disturbance was rated low by all ten patients. Conclusions While the patients’ face-down posture considerably varied over time in extent and continuity, the assessment might lead to optimizing the patients’ compliance with the optimal position. Results showed an excellent acceptance of the motion sensor.
Keywords Posturing . Face-down . Sensor . Data logging M. A. Leitritz (*) : F. Ziemssen : B. Voykov : K. U. Bartz-Schmidt Centre for Ophthalmology, University Eye-Hospital, Eberhard Karls University of Tuebingen, Schleichstr. 12, 72076 Tuebingen, Germany e-mail: [email protected]
Introduction Since the pilot study by Kelly published in 1991 that reported on vitrectomy as a treatment option in cases with idiopathic macular holes, many discussions about the best posturing strategy with respect to face positions continue to occur [1–3]. Dhawahir-Scala could not find any significant differences between patients who postured face down and those who did not [4], while some clinicians recommend a consequent face-down position [5, 6], other investigators do not [7–9]. Efforts to increase patient acceptance and compliance with respect to face-down positions were done and resulted in solutions such as adapted surgery or treatment procedures[9], prone positioning supports [5, 10], or holed mattresses [6]. Schaefer et al. furthermore documented the patient compliance with the help of a temperature logger or patient reports [5], while Shah et al. adapted their face-down time recommendations to the imaging results at 1 day after surgery to shorten posturing periods for patients [11]. The latter step also sought to increase patient satisfaction [12]. Verma et al. reported on an electronic device to evaluate posturing. The device consisted of an ear piece with a mercury switch that was cable-connected to an external logger [13]. Within our pilot study, we investigated the use of a small gravity- and tilt-compensated, head-fixed sensor providing a data-logging function to measure the compliance of patients after macular hole surgery, based on the recommendation previously given on a strict facedown positioning. The purpose of this pilot study was to assess the usability of such a device in principle to measure the inclination for a measurement time of 24 h. Furthermore, the tolerability of wearing such a device should be reported.
Graefes Arch Clin Exp Ophthalmol
Fig. 1 Left Electronic components fixed inside a plastic case. Middle Headband with sensor case and adjustable lock. Right Sensor placed on left side of patient’s head with rotation axes (x, y, z) and pitch angle (p) between sensor inclination axis and horizontal axis
Methods Sensor For measuring the head position, we used an inertial measurement unit (9DOF-Razor-v22, SparkFun Electronics, Boulder, CO, USA), which was connected to a serial data logger (OpenLog, SparkFun Electronics, Boulder, USA). Measurements were saved on a memory card (micro SecureDigital 2 gigabyte, SanDisk Corporation, Milpitas, CA, USA). The electric power supply was provided with a 3-V lithium battery (CR123A, VARTA Consumer Batteries GmbH & Co. KGaA, Ellwangen, Germany) combined with a 3.3-V DC-DC (DC: direct current) converter (NCP1402-3.3 V Step-Up Breakout, SparkFun Electronics, Boulder, CO, USA). All components Fig. 2 Exemplary head positions. Motion axes are shown as colored overlay (blue x-axis, red y-axis, yellow z-axis). At the bottom of each image, inclination values for the presented head position are shown
were placed inside a plastic box (dimensions: 72×26×50 mm) that was mounted on an elastic headband (width: 30 mm) with a self-constructed flat and adjustable lock (total weight of components: 57 g without battery, 72 g with battery) (Fig. 1). The logging interval was set to two measurements per second. Following the recommendations of the local ethic committee, the technical harmlessness of the sensor device was tested and approved by the in-house technical assistance. Patients After obtaining written informed consent, a sensor was attached within the first 5 h after macular hole surgery to the patients’ heads on the side of the treated eye (Fig. 2). The only inclusion criterion was the suitability of a patient for macular
Graefes Arch Clin Exp Ophthalmol Fig. 3 Graphics showing whether face-down position (yaxis) of more than 45° is followed over 24-h measurements (x-axis) for each subject. Daytimemeasurements are marked by the suns, nightthime-measurements by moons respectively
Graefes Arch Clin Exp Ophthalmol
hole surgery. An early study dropout was possible, e.g., because of nausea after surgery. All patients received detailed guidance instructions to remain in the face-down position as strictly as possible. Patients were asked to wear the sensors for 24 h. The position of the sensor due to the horizontal axis was measured as pitch (Fig. 1). An eudermic pen was used to mark the position of the headband. With this simple method, displacements of ≥1 mm could be detected. The correct fitting of the system was checked at regular time intervals of 4 h. After removal of the sensors, patients were interviewed regarding pain or disturbances during the measurement period.
Data The collected data (inclination, time) were copied from the memory card to a personal computer and descriptively analyzed using a statistical program (JMP 10.0, SAS Institute, Cary, NC, USA). All data were anonymously analyzed in accordance with strict German directives on information security and data protection. The investigation followed the tenets of the Declaration of Helsinki. Approval of the local ethic committee was obtained before the analysis of the data.
Table 1 Portions with face-down position for 24 h and only during the daytime Patient
Portion (%) of 24 h with face-down >45° (portion in the daytime)
Tolerability
001 002
26 (6) 5 (5)
003 004 005 006
44 (50) 20 (11) 16 (27) 2 (2)
No disturbances; no pain Slight disturbances with mild pressure (headband) problems; no pain No disturbances; no pain No disturbances; no pain No disturbances; no pain Temporary displacement; no pain
007 008 009 010
17 (25) 24 (20) 14 (9) 11 (18)
No disturbances; no pain No disturbances; no pain No disturbances; no pain No disturbances; no pain
Discussion Within this survey we proved the functional efficiency of a posture sensor, which is gravity- and tilt-compensated. The measured inclination values indicated a low time (45° was 18 % within 24 h and 17 % in the daytime. Median inclination over all measurements of all patients was −6.7° (min: −89.7° max: 90°) (Fig. 4). At the 3-month examination, every macular hole was closed in this small pilot trial (anatomic success).
30 20 10 0 -10 -20 -30 -40 -50 -60
face-down
-70 -80 -90 25000
50000
75000
100000 125000 150000
Number of measurements Fig. 4 Number of measurements (x-axis) and their degrees of inclination (y-axis) on the base of the measurements of all patients. Positive values mean face-up, negative face-down, respectively
Graefes Arch Clin Exp Ophthalmol
The tolerability to wear the sensor device reported by the patients was good. Although many surveys have analyzed and debated the need for and the duration of a face-down posture [2–6, 14], there is a lack of compliance controls. In most cases, the intervention being tested was advice to posture rather than posturing itself. Schaefer et al. used a temperature sensor to evaluate the times in which the tested prone-positioning support was used, but there was no similar system for the control group without this supporting system [5]. Verma et al. evaluated posturing after macular hole surgery with the help of the Maculog device with a mercury switch [13]. Prima facie, this system seems to be very similar to our presented electronic device, but there are essential differences. The switch used by Verma et al. is a simple tilt switch that works with a small bubble of liquid mercury that opens and closes an electrical contact. The toxicity of mercury, as well as the gravitational sensitivity, the absence of a tilt compensation, and the low operating speed, limit its sensitivity for use. The electronic sensor consists of several positioning tools, such as an accelerometer, a magnetometer, and a gyroscope. Therefore, we were able to measure the exact inclination angle. Due to the various sensor systems, acceleration (e.g., walking) and tilt (e.g., while sleeping) forces are compensated for. Furthermore, the system needs no cables or connections outside the box, and easy disinfection of the headband and box was guaranteed. Due to the fact that an absolute stable fixation on the patients head would not be possible or interfere with the wearing comfort, we used an eudermic pen to mark the headband. Hereafter, the correct fitting of the system could be checked at regular time intervals in order to check for or respectively to avoid displacement. With attention to the patients’ reports regarding any incidents, we could only document two problems with the headband. An early dropout of two patients before starting the measurements was explainable due to illness and nausea after general anesthesia. One patient was “lost” because of nonadherence. The results of ten evaluable patient records showed a daily face-down posture time, which seems to be rather short. Compared to the reports of Verma et al., our portions of face-down times at daytime are much lower [13] but calculated over 24 h they are higher. More intense instruction of patients, e.g., as discussed by Waterman et al. [15], could increase the compliance. A bias that came through the sensor could be that patients with a sensor take more care to comply with the given instructions to remain face down (greater awareness, feeling permanently observed). A technical option to improve the adherence could be seen in sensor feedback, which is the next planned step after our pilot study. In the case of forgetfulness and as positive trigger in the case of compliance a feedback is planned as an audio or vibration feedback that depends on the measured inclination
angle (tone or vibration if the predetermined posture is compromised). Further efforts are also planned to miniaturize sensor dimensions in order to further increase patient comfort and acceptance. Hereafter, measurement periods of more than 24 h (e.g., 3 days, 1 week), which assume that the patients use the sensor device also at home, are planned. Other indications for this position sensor might be the posturing (with tilt measurements) in cases of retinal detachment before surgery or following inferior retinectomy. Further questions that we plan to answer are: Can we measure a negative dependency between adherence and duration of posturing? Are there different effects resulting from different instruction tactics (verbal, drawings, etc.)? Is there a different patient population at higher risk of being noncompliant? To summarize, we can confirm a good function and acceptance of our gravity- and tilt-compensated head-fixed sensor with the data-logging function to measure compliance of patients after macular hole surgery. Further studies have to clarify how the device can be improved to achieve a better posturing, also in other retinal diseases.
References 1. Kelly NE, Wendel RT (1991) Vitreous surgery for idiopathic macular holes. Results of a pilot study. Arch Ophthalmol 109:654–659 2. Chandra A, Charteris DG, Yorston D (2011) Posturing after macular hole surgery: a review. Ophthalmol J Int d'ophtalmol Int J Ophthalmol Zeitschrift fur Augenheilkunde 226(Suppl 1):3–9 3. Solebo AL, Lange CAK, Bunce C, Bainbridge JW (2011) Face-down positioning or posturing after macular hole surgery. Cochrane Database Syst Rev (12):CD008228. doi: 10.1002/14651858. CD008228.pub2 4. Dhawahir-Scala FE, Maino A, Saha K, Mokashi AA, McLauchlan R, Charles S (2008) To posture or not to posture after macular hole surgery. Retina 28:60–65 5. Schaefer H, Koss MJ, Singh P, Koch F (2012) Significant Improvement in Compliance with the face-down position after vitrectomy and gas tamponade. Klin Monatsbl Augenheilkd 229:928– 936 6. Krohn J (2005) Duration of face-down positioning after macular hole surgery: a comparison between 1 week and 3 days. Acta Ophthalmol Scand 83:289–292 7. Nadal J, Delas B, Pinero A (2012) Vitrectomy without face-down posturing for idiopathic macular holes. Retina 32:918–921 8. Carvounis PE, Kopel AC, Kuhl DP, Heffez J, Pepple K, Holz ER (2008) 25-gauge vitrectomy using sulfur hexafluoride and no prone positioning for repair of macular holes. Retina 28:1188–1192 9. Iezzi R, Kapoor KG (2013) No face-down positioning and broad internal limiting membrane peeling in the surgical repair of idiopathic macular holes. Ophthalmology. doi:10.1016/j.ophtha.2013.06.001 10. Cullen R (1998) Macular hole surgery: helpful tips for preoperative planning and postoperative face-down positioning. J Ophthalmic Nurs Technol 17:179–181 11. Shah SP, Manjunath V, Rogers AH, Baumal CR, Reichel E, Duker JS (2013) Optical coherence tomography-guided facedown positioning for macular hole surgery. Retina 33:356–362
Graefes Arch Clin Exp Ophthalmol 12. Madgula IM, Costen M (2008) Functional outcome and patient preferences following combined phaco-vitrectomy for macular hole without prone posturing. Eye 22:1050–1053 13. Verma D, Jalabi MW, Watts WG, Naylor G (2002) Evaluation of posturing in macular hole surgery. Eye 16:701–704
14. Tatham A, Banerjee S (2010) Face-down posturing after macular hole surgery: a meta-analysis. Br J Ophthalmol 94:626–631 15. Waterman H, Harker R, MacDonald H, McLaughlan R, Waterman C (2005) Evaluation of an action research project in ophthalmic nursing practice. J Adv Nurs 52:389–398
RETINAL DISORDERS
Usability of a gravity- and tilt-compensated sensor with data logging function to measure posturing compliance in patients after macular hole surgery: a pilot study Martin Alexander Leitritz & Focke Ziemssen & Bogomil Voykov & Karl Ulrich Bartz-Schmidt
Received: 5 September 2013 / Revised: 25 October 2013 / Accepted: 28 October 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Background To investigate the use of a small gravity- and tiltcompensated, head-fixed sensor with data-logging function to measure compliance and head posture of patients after macular hole surgery based on the recommendation of a face-down position. Main outcome measures were the median inclination, the times with correct or incorrect head position and the acceptance/annoyance of a data-logging device. Methods A small battery-driven electronic sensor device with gravity and tilt compensations was placed within a plastic box and fixed on a patient’s head with a headband. Face-down position data were logged every half second for 24 h after macular hole surgery and were stored on a memory card. Results Thirteen patients were involved (seven females, six males, median age, 68 years, range, 50–75 years), two cases with early dropout. Ten of 11 datasets could be evaluated showing a complete data record file. The average percentage for face-down >45° was 18 % within 24 h and 17 % in the daytime. The median inclination was −6.7° (min: −89.7° max: 90°). The sensor system was well tolerated and disturbance was rated low by all ten patients. Conclusions While the patients’ face-down posture considerably varied over time in extent and continuity, the assessment might lead to optimizing the patients’ compliance with the optimal position. Results showed an excellent acceptance of the motion sensor.
Keywords Posturing . Face-down . Sensor . Data logging M. A. Leitritz (*) : F. Ziemssen : B. Voykov : K. U. Bartz-Schmidt Centre for Ophthalmology, University Eye-Hospital, Eberhard Karls University of Tuebingen, Schleichstr. 12, 72076 Tuebingen, Germany e-mail: [email protected]
Introduction Since the pilot study by Kelly published in 1991 that reported on vitrectomy as a treatment option in cases with idiopathic macular holes, many discussions about the best posturing strategy with respect to face positions continue to occur [1–3]. Dhawahir-Scala could not find any significant differences between patients who postured face down and those who did not [4], while some clinicians recommend a consequent face-down position [5, 6], other investigators do not [7–9]. Efforts to increase patient acceptance and compliance with respect to face-down positions were done and resulted in solutions such as adapted surgery or treatment procedures[9], prone positioning supports [5, 10], or holed mattresses [6]. Schaefer et al. furthermore documented the patient compliance with the help of a temperature logger or patient reports [5], while Shah et al. adapted their face-down time recommendations to the imaging results at 1 day after surgery to shorten posturing periods for patients [11]. The latter step also sought to increase patient satisfaction [12]. Verma et al. reported on an electronic device to evaluate posturing. The device consisted of an ear piece with a mercury switch that was cable-connected to an external logger [13]. Within our pilot study, we investigated the use of a small gravity- and tilt-compensated, head-fixed sensor providing a data-logging function to measure the compliance of patients after macular hole surgery, based on the recommendation previously given on a strict facedown positioning. The purpose of this pilot study was to assess the usability of such a device in principle to measure the inclination for a measurement time of 24 h. Furthermore, the tolerability of wearing such a device should be reported.
Graefes Arch Clin Exp Ophthalmol
Fig. 1 Left Electronic components fixed inside a plastic case. Middle Headband with sensor case and adjustable lock. Right Sensor placed on left side of patient’s head with rotation axes (x, y, z) and pitch angle (p) between sensor inclination axis and horizontal axis
Methods Sensor For measuring the head position, we used an inertial measurement unit (9DOF-Razor-v22, SparkFun Electronics, Boulder, CO, USA), which was connected to a serial data logger (OpenLog, SparkFun Electronics, Boulder, USA). Measurements were saved on a memory card (micro SecureDigital 2 gigabyte, SanDisk Corporation, Milpitas, CA, USA). The electric power supply was provided with a 3-V lithium battery (CR123A, VARTA Consumer Batteries GmbH & Co. KGaA, Ellwangen, Germany) combined with a 3.3-V DC-DC (DC: direct current) converter (NCP1402-3.3 V Step-Up Breakout, SparkFun Electronics, Boulder, CO, USA). All components Fig. 2 Exemplary head positions. Motion axes are shown as colored overlay (blue x-axis, red y-axis, yellow z-axis). At the bottom of each image, inclination values for the presented head position are shown
were placed inside a plastic box (dimensions: 72×26×50 mm) that was mounted on an elastic headband (width: 30 mm) with a self-constructed flat and adjustable lock (total weight of components: 57 g without battery, 72 g with battery) (Fig. 1). The logging interval was set to two measurements per second. Following the recommendations of the local ethic committee, the technical harmlessness of the sensor device was tested and approved by the in-house technical assistance. Patients After obtaining written informed consent, a sensor was attached within the first 5 h after macular hole surgery to the patients’ heads on the side of the treated eye (Fig. 2). The only inclusion criterion was the suitability of a patient for macular
Graefes Arch Clin Exp Ophthalmol Fig. 3 Graphics showing whether face-down position (yaxis) of more than 45° is followed over 24-h measurements (x-axis) for each subject. Daytimemeasurements are marked by the suns, nightthime-measurements by moons respectively
Graefes Arch Clin Exp Ophthalmol
hole surgery. An early study dropout was possible, e.g., because of nausea after surgery. All patients received detailed guidance instructions to remain in the face-down position as strictly as possible. Patients were asked to wear the sensors for 24 h. The position of the sensor due to the horizontal axis was measured as pitch (Fig. 1). An eudermic pen was used to mark the position of the headband. With this simple method, displacements of ≥1 mm could be detected. The correct fitting of the system was checked at regular time intervals of 4 h. After removal of the sensors, patients were interviewed regarding pain or disturbances during the measurement period.
Data The collected data (inclination, time) were copied from the memory card to a personal computer and descriptively analyzed using a statistical program (JMP 10.0, SAS Institute, Cary, NC, USA). All data were anonymously analyzed in accordance with strict German directives on information security and data protection. The investigation followed the tenets of the Declaration of Helsinki. Approval of the local ethic committee was obtained before the analysis of the data.
Table 1 Portions with face-down position for 24 h and only during the daytime Patient
Portion (%) of 24 h with face-down >45° (portion in the daytime)
Tolerability
001 002
26 (6) 5 (5)
003 004 005 006
44 (50) 20 (11) 16 (27) 2 (2)
No disturbances; no pain Slight disturbances with mild pressure (headband) problems; no pain No disturbances; no pain No disturbances; no pain No disturbances; no pain Temporary displacement; no pain
007 008 009 010
17 (25) 24 (20) 14 (9) 11 (18)
No disturbances; no pain No disturbances; no pain No disturbances; no pain No disturbances; no pain
Discussion Within this survey we proved the functional efficiency of a posture sensor, which is gravity- and tilt-compensated. The measured inclination values indicated a low time (45° was 18 % within 24 h and 17 % in the daytime. Median inclination over all measurements of all patients was −6.7° (min: −89.7° max: 90°) (Fig. 4). At the 3-month examination, every macular hole was closed in this small pilot trial (anatomic success).
30 20 10 0 -10 -20 -30 -40 -50 -60
face-down
-70 -80 -90 25000
50000
75000
100000 125000 150000
Number of measurements Fig. 4 Number of measurements (x-axis) and their degrees of inclination (y-axis) on the base of the measurements of all patients. Positive values mean face-up, negative face-down, respectively
Graefes Arch Clin Exp Ophthalmol
The tolerability to wear the sensor device reported by the patients was good. Although many surveys have analyzed and debated the need for and the duration of a face-down posture [2–6, 14], there is a lack of compliance controls. In most cases, the intervention being tested was advice to posture rather than posturing itself. Schaefer et al. used a temperature sensor to evaluate the times in which the tested prone-positioning support was used, but there was no similar system for the control group without this supporting system [5]. Verma et al. evaluated posturing after macular hole surgery with the help of the Maculog device with a mercury switch [13]. Prima facie, this system seems to be very similar to our presented electronic device, but there are essential differences. The switch used by Verma et al. is a simple tilt switch that works with a small bubble of liquid mercury that opens and closes an electrical contact. The toxicity of mercury, as well as the gravitational sensitivity, the absence of a tilt compensation, and the low operating speed, limit its sensitivity for use. The electronic sensor consists of several positioning tools, such as an accelerometer, a magnetometer, and a gyroscope. Therefore, we were able to measure the exact inclination angle. Due to the various sensor systems, acceleration (e.g., walking) and tilt (e.g., while sleeping) forces are compensated for. Furthermore, the system needs no cables or connections outside the box, and easy disinfection of the headband and box was guaranteed. Due to the fact that an absolute stable fixation on the patients head would not be possible or interfere with the wearing comfort, we used an eudermic pen to mark the headband. Hereafter, the correct fitting of the system could be checked at regular time intervals in order to check for or respectively to avoid displacement. With attention to the patients’ reports regarding any incidents, we could only document two problems with the headband. An early dropout of two patients before starting the measurements was explainable due to illness and nausea after general anesthesia. One patient was “lost” because of nonadherence. The results of ten evaluable patient records showed a daily face-down posture time, which seems to be rather short. Compared to the reports of Verma et al., our portions of face-down times at daytime are much lower [13] but calculated over 24 h they are higher. More intense instruction of patients, e.g., as discussed by Waterman et al. [15], could increase the compliance. A bias that came through the sensor could be that patients with a sensor take more care to comply with the given instructions to remain face down (greater awareness, feeling permanently observed). A technical option to improve the adherence could be seen in sensor feedback, which is the next planned step after our pilot study. In the case of forgetfulness and as positive trigger in the case of compliance a feedback is planned as an audio or vibration feedback that depends on the measured inclination
angle (tone or vibration if the predetermined posture is compromised). Further efforts are also planned to miniaturize sensor dimensions in order to further increase patient comfort and acceptance. Hereafter, measurement periods of more than 24 h (e.g., 3 days, 1 week), which assume that the patients use the sensor device also at home, are planned. Other indications for this position sensor might be the posturing (with tilt measurements) in cases of retinal detachment before surgery or following inferior retinectomy. Further questions that we plan to answer are: Can we measure a negative dependency between adherence and duration of posturing? Are there different effects resulting from different instruction tactics (verbal, drawings, etc.)? Is there a different patient population at higher risk of being noncompliant? To summarize, we can confirm a good function and acceptance of our gravity- and tilt-compensated head-fixed sensor with the data-logging function to measure compliance of patients after macular hole surgery. Further studies have to clarify how the device can be improved to achieve a better posturing, also in other retinal diseases.
References 1. Kelly NE, Wendel RT (1991) Vitreous surgery for idiopathic macular holes. Results of a pilot study. Arch Ophthalmol 109:654–659 2. Chandra A, Charteris DG, Yorston D (2011) Posturing after macular hole surgery: a review. Ophthalmol J Int d'ophtalmol Int J Ophthalmol Zeitschrift fur Augenheilkunde 226(Suppl 1):3–9 3. Solebo AL, Lange CAK, Bunce C, Bainbridge JW (2011) Face-down positioning or posturing after macular hole surgery. Cochrane Database Syst Rev (12):CD008228. doi: 10.1002/14651858. CD008228.pub2 4. Dhawahir-Scala FE, Maino A, Saha K, Mokashi AA, McLauchlan R, Charles S (2008) To posture or not to posture after macular hole surgery. Retina 28:60–65 5. Schaefer H, Koss MJ, Singh P, Koch F (2012) Significant Improvement in Compliance with the face-down position after vitrectomy and gas tamponade. Klin Monatsbl Augenheilkd 229:928– 936 6. Krohn J (2005) Duration of face-down positioning after macular hole surgery: a comparison between 1 week and 3 days. Acta Ophthalmol Scand 83:289–292 7. Nadal J, Delas B, Pinero A (2012) Vitrectomy without face-down posturing for idiopathic macular holes. Retina 32:918–921 8. Carvounis PE, Kopel AC, Kuhl DP, Heffez J, Pepple K, Holz ER (2008) 25-gauge vitrectomy using sulfur hexafluoride and no prone positioning for repair of macular holes. Retina 28:1188–1192 9. Iezzi R, Kapoor KG (2013) No face-down positioning and broad internal limiting membrane peeling in the surgical repair of idiopathic macular holes. Ophthalmology. doi:10.1016/j.ophtha.2013.06.001 10. Cullen R (1998) Macular hole surgery: helpful tips for preoperative planning and postoperative face-down positioning. J Ophthalmic Nurs Technol 17:179–181 11. Shah SP, Manjunath V, Rogers AH, Baumal CR, Reichel E, Duker JS (2013) Optical coherence tomography-guided facedown positioning for macular hole surgery. Retina 33:356–362
Graefes Arch Clin Exp Ophthalmol 12. Madgula IM, Costen M (2008) Functional outcome and patient preferences following combined phaco-vitrectomy for macular hole without prone posturing. Eye 22:1050–1053 13. Verma D, Jalabi MW, Watts WG, Naylor G (2002) Evaluation of posturing in macular hole surgery. Eye 16:701–704
14. Tatham A, Banerjee S (2010) Face-down posturing after macular hole surgery: a meta-analysis. Br J Ophthalmol 94:626–631 15. Waterman H, Harker R, MacDonald H, McLaughlan R, Waterman C (2005) Evaluation of an action research project in ophthalmic nursing practice. J Adv Nurs 52:389–398
