Retinal sensitivity and fixation changes 1 year after triamcinolone acetonide assisted internal limiting membrane peeling for macular hole surgery--a MP-1 microperimetric study

Clinical utilization of microperimetry in ophthalmic surgery: A narrative review

Microperimetry is an emerging technology that provides concurrent analysis of retinal structure and function by combining retinal sensitivity and fixation analysis with fundus imaging. We summarize the substantial evidence validating the evolving role of microperimetry as an adjunctive assessment of visual function in the perioperative setting. We show that microperimetry provides useful complementary information to other established imaging and functional modalities in the perioperative setting for a wide range of vitreoretinal surgical procedures, as well as in cataract and refractive surgeries. This includes preoperative uses such as prognostication of visual and anatomical outcomes, timing of surgical intervention, and assessment of patient suitability for surgery-as well as postoperative uses including quantification of visual recovery, investigation of unexplained postoperative vision loss, and informing expected long term functional outcomes.

What Is a Preferred Retinal Locus?

This review examines the concept of the preferred retinal locus (PRL) in patients with macular diseases. Considering monocular and binocular viewing, we (a) explain how to identify the PRL and discuss the pitfalls associated with its measurement, (b) review the current hypotheses for PRL development, (c) assess whether the PRL is the new reference point of the ocular motor system, and discuss (d) the functional and (e) the clinical implications of the PRL. We conclude that the current definition of the PRL is probably incomplete and should incorporate the need to evaluate the PRL in the framework of binocular viewing. We emphasize the need for more research.

Biofeedback Training after Successful Inverted Internal Limiting Membrane (ILM)-Flap Technique for High Myopic Macular Hole

BACKGROUND

Microperimetric biofeedback training improved visual acuity and fixation stability in patients who previously underwent macular surgery. We aimed to compare the functional results of biofeedback training with the standard of care in patients who underwent successful inverted Internal Limiting Membrane (ILM)-flap technique for high myopic macular holes (hMMH).

METHODS

This was a retrospective, comparative, cohort study. Patients with hMMH after surgical hole closure underwent microperimetric biofeedback using structured light stimulus plus acoustic tone (n = 12; Biofeedback) or standard of care with scheduled visits (n = 11; Control). Best-corrected visual acuity, retinal sensitivity at central 12° (RS) and 4° (CRS) with a mean deviation at central 12° (MD), and fixation stability as bivariate contour ellipse area (BCEA 68%, 95%, and 99%) were assessed at baseline and month 1, 3, 6, and 12. The Mann-Whitney test was used to test the difference between the groups.

RESULTS

Baseline functional parameters were not significantly different among the groups. BCVA significantly improved in each group (Biofeedback, p = 0.002; Control, p ≤ 0.02) at all follow-up visits. CRS significantly improved at 6 (p = 0.03) and 12 (p = 0.01) months in the Biofeedback group and at month 12 (p = 0.01) in the Control group. RS (p = 0.001) and MD (p = 0.005) improved at the last follow-up only in the trained group. After training, BCEA 68% and 95% significantly improved (6 and 12 months, p < 0.05). The Biofeedback group had better results in RS (p ≤ 0.02), CRS (p ≤ 0.02), and BCEA 68%, 95%, and 99% (p ≤ 0.01) compared to the Control at all follow-ups. BCVA and MD were better in the Biofeedback group at month 3 (p = 0.01), and month 3 (p = 0.01) and 12 (p = 0.003), respectively.

CONCLUSIONS

Microperimetric biofeedback can increase retinal sensitivity and stabilize fixation better than the standard care over months after a successful inverted ILM-flap for hMMH.

Microstructural and microperimetric comparison of internal limiting membrane peeling and insertion in large idiopathic macular hole

BACKGROUND

The internal limiting membrane (ILM) insertion technique was widely used to treat large macular hole (MH) for the high closure rate. However, the prognosis of closed MH after ILM insertion compared to ILM peeling remains controversial. This study aimed to compare foveal microstructure and microperimeter in large idiopathic MH surgically closed by ILM peeling and ILM insertion.

METHODS

This retrospective, non-randomized, comparative study included patients with idiopathic MH (minimum diameter ≥ 650 μm) who underwent primary pars plana vitrectomy (PPV) with ILM peeling or ILM insertion. The initial closure rate was recorded. Patients with initially closed MHs were divided into two groups according to the surgery methods. The best-corrected visual acuity (BCVA), optical coherence tomography (OCT) and microperimeter-3 (MP-3) outcomes of two groups were compared at baseline, 1 and 4 months postoperatively.

RESULTS

For idiopathic MH (minimum diameter ≥ 650 μm), ILM insertion had a significantly higher initial closure rate than ILM peeling (71.19% vs. 97.62%, P = 0.001). Among 39 patients with initially closed MHs who were on regular follow-up, twenty-one were assigned to the ILM peeling group and 18 to the ILM insertion group. Postoperative BCVA improved significantly in both groups. The final BCVA (logMAR) (0.40 vs. 0.88, P < 0.001), macular hole sensitivity (19.66 dB vs. 14.14 dB, P < 0.001), peripheral sensitivity of macular hole (24.63 dB vs. 21.95 dB, P = 0.005), and fixation stability (FS) within 2 degrees (82.42% vs. 70.57%, P = 0.031) were significantly better and external limiting membrane (ELM) defect (330.14 μm vs. 788.28 μm, P < 0.001) and ellipsoid zone (EZ) defect (746.95 μm vs. 1105.11 μm, P = 0.010) were significantly smaller in the ILM peeling group than in the ILM insertion group.

CONCLUSION

For initially closed MHs (minimum diameter ≥ 650 μm), both ILM peeling and ILM insertion significantly improved the microstructure and microperimeter in the fovea. However, ILM insertion was less efficient at microstructural and functional recovery after surgery.

Correlations between Visual Performance and Chorioretinal Variables after Vitrectomy for the Idiopathic Macular Hole

Purpose

To investigate the relationships between visual function and the retinal and choroid microstructure in idiopathic macular hole patients after surgery.

Methods

A prospective study investigated changes in the fundus structure and visual function in 16 macular hole patients before and after surgery. Patients' best-corrected visual acuity (BCVA) and retinal sensitivity were measured by an EDTRS visual chart and microperimetry (MP1), respectively. The thickness of the retina and the blood supply to the retina and superficial choroid were detected by OCTA, and the choroidal capillary blood flow density was analysed with MATLAB. The thickness of the choroid and the aperture size of the macular hole were detected by Heidelberg OCT.

Results

Compared with before surgery and one month after surgery, the BCVA (3 months: 0.47 ± 0.27, before: 1.02 ± 0.22, 1 month: 0.66 ± 0.27, and P < 0.05) and the central sensitivity of the retina (3 months: 14.88 ± 2.87 dB, before: 8.76 ± 3.27 dB, 1 month: 12.22 ± 3.30 dB, and P < 0.05) were significantly improved three months after surgery. The change in BCVA was significantly correlated with the basal diameter (r = 0.677 and P = 0.004), the minimum diameter (r = 0.585 and P = 0.017), the macular hole cystoid height area index (r = -0.618 and P = 0.011), the central macular hole index (r = -0.727 and P = 0.001), the peripheral macular hole index (r = -0.758 and P = 0.001), the central tractional hole index (r = -0.717 and P = 0.002), the peripheral tractional hole index (r = -0.725 and P = 0.001), and changes in the peripheral blood vessel density of the choroid capillary layer (r = 0.585 and P = 0.0017). The change in central retinal sensitivity was correlated with the change in the superficial foveal avascular zone (FAZ; r = 0.520 and P = 0.039), change in the retinal superficial peripheral blood flow density (r = -0.503 and P = 0.047), change in the deep FAZ (r = 0.599 and P = 0.014), and change in the retinal deep peripheral blood flow density (r = -0.601 and P = 0.014).

Conclusions

The morphology of the macular hole as well as changes to the retinal and choroidal microstructure contributes to the recovery of visual function after surgery.

Evaluation of retinal functional changes after macular hole surgery using heavy brilliant blue G dye for internal limiting membrane staining: A prospective, single blind, randomized controlled trial

Purpose:

To evaluate retinal functional changes after idiopathic macular hole (MH) surgery using heavy brilliant blue G (hBBG) dye for internal limiting membrane (ILM) staining.

Methods:

Forty-four eyes with idiopathic MH were randomized into two groups – 24 eyes undergoing vitrectomy with ILM peeling using hBBG staining and 20 eyes without staining; anatomical and functional status (with microperimetry (MP)) at baseline and during postoperative follow-up were noted and compared.

Results:

All eyes had closure of MH postoperatively and overall baseline MP indices (average threshold, AT; foveal sensitivity, FS) improved significantly at 6 weeks and 6 months of follow-up. AT and FS showed significant improvement at 6 weeks and 6 months from baseline in both individual groups (P < 0.001). Intergroup comparison showed that there was no statistically significant difference in AT and FS values at any point of time (baseline, 6 weeks, 6 months) between staining and no-stain group. No eyes in our cohort had any unexplained visual loss.

Conclusion:

Functional parameters of macula improved significantly after successful MH surgery using hBBG for staining the ILM.

MACULAR SENSITIVITY IN THE AREA OF INTERNAL LIMITING MEMBRANE PEELING IN EYES AFTER PARS PLANA VITRECTOMY WITH THE TEMPORAL INVERTED INTERNAL LIMITING MEMBRANE FLAP TECHNIQUE FOR A FULL-THICKNESS MACULAR HOLE

PURPOSE

To examine the relationship between retinal sensitivity and the area of internal limiting membrane (ILM) peeling during pars plana vitrectomy for a full-thickness macular hole.

METHODS

Twenty-four eyes a minimum of 6 months after temporal inverted flap pars plana vitrectomy for a full-thickness macular hole were included in the study. En face spectral-domain optical coherence tomography images were used to assess margins of the peeled ILM area. Microperimetry was performed to examine retinal sensitivity within the central 10°. Areas of peeled ILM in en face optical coherence tomography images were correlated with the average sensitivity threshold. Retinal sensitivities at the location of each measurement point were compared with structural abnormalities observed in en face spectral-domain optical coherence tomography images.

RESULTS

The mean retinal sensitivity in the area of ILM removal was significantly lower compared with the area of preserved ILM (24.29 ± 3.96 dB vs. 26.19 ± 2.10 dB, P < 0.0001, respectively). The peeled ILM area showed a negative correlation with the average sensitivity threshold (r = -0.56, P < 0.01).

CONCLUSION

A larger area of ILM peeling during temporal inverted flap pars plana vitrectomy for a full-thickness macular hole is related to lower retinal sensitivity in the central macula.

Characteristics and management of macular hole developing after rhegmatogenous retinal detachment repair

PURPOSE

To report characteristics of patients developing full-thickness macular hole (MH) after rhegmatogenous retinal detachment (RRD) repair surgery. We also compared patients developing MH with and without accompanying RRD recurrence regarding anatomical and visual outcomes of MH repair.

DESIGN

Retrospective study.

METHODS

Medical records of patients who developed MH after RRD repair between January 2002 and January 2018 were reviewed.

RESULTS

We performed 1661 primary RRD operations during the study period and 14 of these developed MH, an incidence of 0.8%. Nine patients had their primary RRD repair surgery in another clinic and were referred to our clinic after development of MH. In total 23 patients with MH secondary to RRD repair were included in the study. The type of RRD repair surgery was scleral buckling only in 4 patients (17%), pars plana vitrectomy (PPV) only in 14 patients (61%), and sequential scleral buckling and PPV in 5 patients (22%). Nineteen patients (83%) had macula-off RRD. In 12 patients (52%), MH developed within 3 months after RRD repair. Surgery for MH repair was performed in 18 patients. Postoperative best corrected visual acuity (BCVA) was better than preoperative BCVA in the group with RRD recurrence as well as in the group without RRD recurrence (both P < 0.05). There wasn't a significant difference between these groups regarding postoperative visual gain and anatomical success (P > 0.05).

CONCLUSION

MH can develop after various surgical methods of RRD repair. Anatomic closure and visual acuity gain can be achieved even if patients have accompanying RRD recurrence.

Microperimetric Biofeedback Training after Successful Inverted Flap Technique for Large Macular Hole

Background: Despite the high closure rate of large macular hole (LMH) after surgery, visual recovery is often worse than expected. Microperimetric biofeedback can improve visual function in macular pathologies. We evaluated the efficacy of biofeedback on macular function after successful inverted flap technique for LMH. Methods: In this prospective comparative study, 26 patients after LMH surgical closure were enrolled. The whole sample was equally divided into two groups. In Group 1 (trained), patients underwent a double cycle of microperimetric biofeedback, using structured light stimulus plus acoustic tone; in Group 2 (control), patients underwent scheduled visits. We analyzed visual acuity, retinal sensitivity at central 12° (macular sensitivity, MS) and 4° (central macular sensitivity, CMS), and fixation stability over twelve months. Results: Visual acuity improved mainly in the trained group, without any significant differences between the groups (p > 0.05). Only after training did MS significantly improve (p = 0.01). CMS more significantly improved in the trained (p < 0.001) than the control group (p < 0.01) (Group 1 vs. 2, p = 0.004). Only in the trained group did fixation significantly improve (3 months, p ≤ 0.03; 12 months, p ≤ 0.01). An equality test on matched data confirmed a greater significant improvement of CMS (p ≤ 0.02) at all follow-up and fixation (p ≤ 0.02) at last follow-up after training. Conclusions: Microperimetric biofeedback consolidates and increases the improvement of retinal sensitivity and fixation gained after successful inverted flap technique.

Inverted internal limiting membrane-flap technique for large macular hole: a microperimetric study

Background

Inverted Internal Limiting Membrane (ILM)-flap technique would seem to lead to higher closure rate and better visual acuity than traditional procedure with ILM peeling for the treatment of large macular hole (LMH). Visual acuity recovery does not reveal many other functional changes related to surgical approach. Our purpose was to evaluate macular function and morphology over a 1-year follow-up after inverted ILM-flap technique for LMH by using microperimetry in order to predict visual prognosis.

Methods

This study was a prospective unrandomized single-center study. 23 eyes of 22 patients with idiopathic LMH, with a minimum diameter ranging from 400 to 1000 μm, were included. All patients underwent vitrectomy with inverted ILM-flap technique and gas tamponade. We analyzed macular hole closure rate and functional outcomes including best-corrected visual acuity (BCVA), macular sensitivity (MS) at central 12° and central macular sensitivity (CMS) at central 4°, and fixation behavior as bivariate contour ellipse area (BCEA, degrees²) at 68%, 95%, and 99% of fixation points measured by microperimeter, over a follow-up of 12 months.

Results

The macular hole closure rate was 98%. The BCVA improved from 20/230 (Logmar, 1.06 ± 0.34) to 20/59 (logMar, 0.47 ± 0.45) at last follow-up (p < 0.001). Retinal sensitivity and BCEA significantly improved (MS, p = 0.001; CMS, p < 0.0001; BCEA: 68%, p < 0.01; 95%, p < 0.01; 99%, p = 0.001). Multiple stepwise regression analysis showed the final BCVA was significantly associated with macular hole size (β = 0.002, p = 0.03), preoperative MS (β = − 0.06, p = 0.001) and BCEA at 95% and 99% of fixation points (β = − 0.12, p = 0.01; β = 0.06, p = 0.01).

Conclusions

Inverted ILM-flap technique for LMH results in good morphologic and functional outcomes. Macular hole size and microperimetric parameters as preoperative MS and BCEA have a predictive role on post-surgical visual acuity.

DOUBLE ARCUATE RELAXING RETINOTOMY FOR A LARGE MACULAR HOLE

PURPOSE

To describe double arcuate relaxing retinotomy as an alternative surgical technique in a case with a secondary large macular hole.

METHODS

The management of a patient who developed a large macular hole and macular tractional rhegmatogenous retinal detachment after pars plana vitrectomy for proliferative diabetic retinopathy was retrospectively assessed. Despite surgical procedures, such as dissection of a preretinal membrane from the retina and peeling of the retinal internal limiting membrane, the macular hole could not be closed. In the absence of an alternative method, superior and inferior posterior arcuate, 120° relaxing retinotomies were performed.

RESULTS

At the follow-up, the macular hole closure was confirmed by clinical examination and optical coherence tomography imaging, and visual acuity improved. There were no intraoperative or postoperative complications.

CONCLUSION

In cases of large macular holes, double arcuate relaxing retinotomy can reduce traction, leading to hole closure.

Macular sensitivity in patients with congenital stationary night-blindness

AIM

To evaluate and correlate mean light sensitivity thresholds (MLST) in patients with congenital stationary night-blindness (CSNB) in comparison with healthy subjects using microperimetry (MP1).

METHODS

Eleven patients with CSNB and 13 healthy subjects were compared. In all subjects, static threshold perimetry was performed using MP1 evaluating the central 6 mm of the retina. This central retinal area was divided into three rings through using the ETDRS grid algorithm with an innermost (1 mm), inner (3 mm) and outer ring (6 mm). The MLSTs were acquired in nine sectors of the ETDRS grid. A comparison of MLST was performed between both groups using a t-test (significance level p<0.005).

RESULTS

A significant reduction of MLST in the fovea (innermost ring, 1 mm) was observed for patients with CSNB (7.2±3.90 dB) in comparison to healthy subjects (19.7±0.75; p<0.0001). Similarly, comparison of MLST in all other sectors (superior/inferior/temporal and nasal) within the inner and outer ring revealed a statistically significant reduction in patients with CSNB compared with healthy subjects (p<0.001).

CONCLUSIONS

Examination of macular retinal sensitivity intensity using MP1 revealed for the first time a significant reduction of MLST within the central 6 mm of the retina in patients with CSNB compared with healthy subjects. This finding supports MP1 as an additional diagnostic tool when examining patients with retinal dysfunctions such as CSNB.

Current Clinical Application of Microperimetry: A Review

Microperimetry (MP) is a technology that allows the study of retinal sensitivity at different foveal and parafoveal areas as well as eye fixation. It is a technique of functional evaluation, providing a direct correlation between anatomical and functional outcomes. There are a great variety of studies which evaluate the repeatability or reliability of measurements obtained with this technology and also describe and explore different clinical applications. MP has been shown to be useful in the characterization of sensory and motor conditions, such as amblyopia or nystagmus. Concerning ocular pathology, several studies have confirmed the usefulness of MP for evaluating and analyzing different retinal pathological conditions, such as age-related macular degeneration or glaucoma, and for analyzing the effect of different medical or surgical treatments for these conditions. MP has also been shown to be useful for visual training or rehabilitation in some specific cases.

Microperimetric Assessment after Epiretinal Membrane Surgery: 4-Year Follow-Up

Purpose. To investigate retinal function using microperimetry in patients affected by idiopathic epiretinal membrane (iERM) and cataract who underwent combined surgery: 4-year follow-up. Design. Prospective, interventional case series. Methods. 30 eyes of 30 consecutive patients with iERM and age-related cataract underwent 25-gauge vitrectomy and cataract surgery. At baseline, 90 and 180 days, and 1 and 4 years, we examined retinal mean sensitivity (MS), retinal mean defect (MD), fixation stability, and frequency of microscotomas using MP1 microperimetry. Best-corrected visual acuity (BCVA) and central retinal thickness (CRT) using a spectral domain optical coherence tomography (SD-OCT) were also performed. Results. All patients completed 1-year follow-up, while 23 patients reached last follow-up. Baseline MS and MD (10.48 ± 4.17 and −9.18 ± 4.40 dB) significantly changed at one year (12.33 ± 3.66 and −7.49 ± 3.31 dB, p < 0.01), at four years (14.18 ± 3.46 and −4.66 ± 2.85, p < 0.01), and between one and four years (p < 0.01) after surgery. Compared to baseline, CRT and BCVA significantly changed at one year and remained stable at four years. No variations were observed in fixation stability and frequency of microscotomas compared to baseline. Conclusions. Long-term follow-up using microperimetry seems useful to evaluate patients after iERM surgery: retinal sensitivity changes even when BCVA and CRT remain stable.

Microperimetric Biofeedback Training Improved Visual Acuity after Successful Macular Hole Surgery

Purpose. To evaluate the efficacy of setting a preferred retinal locus relocation target (PRT) and performing Macular Integrity Assessment (MAIA) biofeedback training in patients showing insufficient recovery of best corrected visual acuity (BCVA) despite successful closure of an idiopathic macular hole (MH). Methods. Retrospective interventional case series. Nine eyes of 9 consecutive patients with the decimal BCVA of less than 0.6 at more than 3 months after successful MH surgery were included. A PRT was chosen based on MAIA microperimetry and the patients underwent MAIA biofeedback training. BCVA, reading speed, fixation stability, and 63% bivariate contour ellipse area (BCEA) were evaluated before and after the training. Statistical analysis was carried out using paired Student's t-test. Results. PRT was chosen on the nasal side of the closed MH fovea in 8 patients. After the MAIA training, BCVA improved in all patients. The mean logMAR value of BCVA significantly improved from 0.33 to 0.12 (p = 0.007). Reading speed improved in all patients (p = 0.29), fixation stability improved in 5 patients (p = 0.70), and 63% BCEA improved in 7 patients (p = 0.21), although these improvements were not statistically significant. Conclusion. MAIA biofeedback training improved visual acuity in patients with insufficient recovery of BCVA after successful MH surgery.

Macular pucker: to peel or not to peel the internal limiting membrane? A microperimetric response

BACKGROUND

To compare functional and anatomical outcomes after idiopathic macular pucker removal between eyes that underwent internal limiting membrane (ILM) peeling and eyes that did not.

METHODS

In this multicentric, randomized clinical trial, 60 eyes of 60 patients affected with idiopathic macular pucker were enrolled. Thirty eyes underwent 23-gauge pars plana vitrectomy associated with ILM peeling ("ILM peeling group"), whereas 30 eyes did not undergo ILM peeling ("ILM not peeling group"). Retinal sensitivity, frequency of microscotomas, and all the other microperimetric parameters were tested by MP1 microperimetry. Best-corrected visual acuity was investigated with the Early Treatment Diabetic Retinopathy Study chart. Anatomical outcomes were analyzed with spectral domain optical coherence tomography.

RESULTS

After a 12-month follow-up, the mean retinal sensitivity in the 4° central area showed a greater and faster recovery in the ILM not peeling group than in the ILM peeling group (P = 0.041). The number of absolute microscotomas (0 dB) within the 12° central retinal area was significantly higher in the ILM peeling group than in the ILM not peeling group (P = 0.044).

CONCLUSION

The ILM not peeling group seems to show better outcomes than the ILM peeling group as measured by mean retinal sensitivity and number of microscotomas after a 12-month follow-up.

Correlation between Retinal Changes and Visual Function in Late-Stage Vogt-Koyanagi-Harada Disease: An Optical Coherence Tomography Study

Purpose. To characterize the optical coherence tomography (OCT) findings in late-stage Vogt-Koyanagi-Harada (VKH) disease and its correlation with visual function. Methods. The records of patients with late-stage VKH disease (defined as ≥12 months from disease onset) were retrospectively reviewed. The analysis focused on the OCT findings and microperimetry, in addition to the possible correlation between morphology and functional findings. Results. Twenty-nine patients (58 eyes) were included. Mean age at onset was 34.24 ± 10.67 years. The OCT revealed that the outer retina and retinal pigment epithelium (RPE) were mainly affected. These effects included RPE thickening and breakage or disappearance of the cone outer segment tip (COST) line and/or inner segment/outer segment (IS/OS) junction. The COST line and IS/OS results were related to macular function and the interval between symptom onset and initiation of high-dose corticosteroid treatment (all P < 0.01). Eyes with intact COST lines demonstrated intact IS/OS and normal RPE layers as well as better visual function and normal retinal sensitivity. Conclusions. The OCT findings are strongly correlated with macular function, as well as other clinical findings in late-stage VKH. With respect to the COST line and retinal sensitivity especially, the OCT and microperimetry findings may be useful for evaluating later-stage VKH.

Intrasession repeatability of fixation stability assessment with the Nidek MP-1

PURPOSE

This study aims to determine the intrasession repeatability and agreement using two methods to analyze fixation stability recorded during microperimetry in patients with macular disease.

METHODS

Fifty patients with macular disease were enrolled prospectively to perform two consecutive microperimetry examinations on the Nidek microperimeter-1 (MP-1) using the same 1° red cross for fixation, Humphrey 10 to 2 grid of 68 test loci, 4 to 2 stair-case strategy, and 200 ms duration stimuli of Goldmann III size. Fixational eye movement was recorded during the two microperimetry examinations, and fixation stability was analyzed in two ways: (1) qualitatively through fixation stability grade (unstable, relatively unstable, and stable) and (2) quantitatively by calculating the logarithm of the bivariate contour ellipse area (logBCEA) that encompassed 68% of fixation points. Agreement and repeatability were assessed by unweighted kappa and the coefficient of repeatability.

RESULTS

The mean (SD) visual acuity (VA) was 0.34 (0.32) logarithm of minimum angle of resolution. The mean (SD) duration of microperimetry was 13 (4) and 12 (4) min during the first and second measurements, respectively. During the first test, 10, 19, and 21 patients had unstable, relatively unstable, and stable fixation stability grading, respectively. Seventy percent (kappa: 0.53) of the fixation stability grading remained unchanged during repeat measurement. Of the remaining, 14% had a one-step decline and 16% had a one-step improvement in stability grading. The mean logBCEA were 4.28 and 4.24 in first and second tests, respectively (p = 0.43). The coefficient of repeatability for logBCEA was 0.61.

CONCLUSIONS

The logBCEA method of analysis for fixation stability assessment is preferable. If logBCEA derived from a microperimetry task is used as part of the core outcome set in a clinical trial, a change of >0.61 may be considered to exceed the limit of test-retest variability.