Disc Configuration as a Risk and Prognostic Factor in NAION: The Impact of Cup to Disc Ratio,Disc Diameter,and Crowding Index

Purpose: The presence of the so called disc at risk (a small disc with no cupping) has been considered the main risk factor for the development of non-arteritic anterior ischemic optic neuropathy (NAION). However its role as a prognostic factor has not been studied. Our aim was to determine the weight of disc configuration as a risk and a prognostic factor for NAION.

Methods: Case control study. Forty eyes of 40 patients who were diagnosed with NAION between 2008 and 2017, and 120 controls (3 controls for each patient) were included in the study. Disc diameter (DD), cup to disc ratio (CDR), and peripapillar retinal nerve fiber layer thickness (RNFLT) of the non-affected eye were measured using optic coherence tomography (3D OCT 2000, Topcon). Crowding index (CI) was defined as the quotient of average RNFLT and disc area. Mean deviation (MD) at the time of diagnosis and at least three months later was determined using a Humphrey Visual Field Analyzer (SITA standard 24-2 strategy). Visual acuity (VA) was measured using Snellen charts and transformed into LogMAR values.

Results: Only CDR was found to be a risk factor for NAION. No correlationship was found between CI and visual loss.

Conclusions: DD and CI did not show value as either prognostic or risk factors. Glial tissue may be a part of the content of the optic disc as important as axons. Our results are in line with the latest studies about NAION pathophysiology. Contrary to classic thinking, these papers have not found smaller disc diameters, but smaller values of lamina cribosa depth in NAION patients.     

Agreement in Measurement of Optic Cup-to-Disc Ratio with Stereo Biomicroscope Funduscopy and Digital Image Analysis: Results from the Nigeria National Blindness and Visual Impairment Survey

Purpose: To determine agreement in estimations of vertical cup-to-disc ratio (VCDR) between clinical stereo-biomicroscopic funduscopy and digital fundus image analysis.

Methods: Systematic sampling of 1-in-7 from a sample of 13,591 participants aged ≥40 years gave a subsample who were examined in detail. VCDR was estimated clinically by 60 diopter aspheric lens biomicroscopic funduscopy (c-VCDR) and by digital fundus images (i-VCDR) graded at the Moorfields Eye Hospital Reading Centre. Spearman’s correlation coefficient, paired t-test and the Bland-Altman method to assess limits of agreement (LOA) between the two methods were applied.

Results: Of 1759 participants in the subsample, 848 participants (48%) with normal frequency doubling technology (FDT) visual fields and data for i-VCDR and c-VCDR in both eyes (n = 1696 eyes) were included in the analysis. By absolute difference of VCDR values for each eye between the two methods, 1585 eyes (94%) differed by ≤0.2. Mean i-VCDR was 0.381 (standard deviation, SD 0.156), and mean c-VCDR 0.321 (SD 0.145). i-VCDRs were significantly larger by a mean difference of 0.061 (SD 0.121; 95% confidence interval, CI, 0.055–0.066; p < 0.001). The 95% LOA assessed by the Bland-Altman method were lower limit ?0.182 (95% CI ?0.192 to ?0.172) and upper limit 0.303 (95% CI 0.293–0.313). The 95% LOA intervals narrowed with higher VCDR.

Conclusion: Digital image analysis and clinical assessment are two distinct methods to measure VCDR; with larger i-VCDRs in this survey. Applying i-VCDR cut-off values to c-VCDR measurements in the Nigeria Blindness Survey might have underestimated glaucoma prevalence. It is recommended that all participants in glaucoma surveys have VCDR by digital image measurement.     

Assessing Responses of the Macula in Patients with Macular Holes using a New System Measuring Localized Visual Acuity and the mfERG

Purpose: To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. Methods: We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We measured local visual acuity thresholds at 27 discrete locations within 21° diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function of visual field location, and local ERG responses within 45° diameter using the mfERG. Results: In the affected eyes, the mean FFIS visual acuity thresholds were significantly elevated within the central 21° diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8° in affected eyes. In the central 2°, 4 out of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. Conclusions: Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range).     

Partial Visual Rehabilitation Using a Toric Implantable Collamer Lens in a Patient with Keratoconus: A Case Report with 20 Months of Follow-up

We report the case of a 37-year-old man with a high myopic keratoconus eye that was treated with a posterior chamber toric implantable collamer lens (ICL) in Korea. The patient had a history of contact lens intolerance and did not want to have a corneal transplantation. His uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity were 0.02 and 0.4 in the left eye, respectively. Preoperatively, the manifest refraction was -12.0 -3.5 × 30A. Postoperatively, the manifest refraction was -1.75 × 180A. UCVA improved markedly after implantation. No intraoperative or postoperative complications were observed during 20 months of follow-up. Toric ICL implantation may be a possible alternative surgical option for the visual rehabilitation of high myopic astigmatism in keratoconus patients with rigid gas permeable contact lens intolerance and in patients who do not want to get a corneal transplant.     

Unusual Posterior Hyaloid Strand in a Young Child with Optic Disc Pit Maculopathy: Intraoperative and Histopathological Findings

Background The mechanism responsible for optic disc pit maculopathy is unclear, but abnormal vitreous structures, including the anomalous Cloquets canal at the optic disc pit, have been suggested as important factors.Case We report the intraoperative and ultrastructual findings of an unusual posterior vitreous strand in the eye of an 8-year-old girl with optic disc pit maculopathy.Observations The patient presented with decreased vision in the left eye. Examination of the left eye revealed a best-corrected visual acuity (VA) of 0.08 and a macular detachment associated with an optic disc pit. Vitrectomy was performed with the adjunctive use of triamcinolone acetonide intraoperatively. The presence of an unusual posterior hyaloid strand tightly attached to the margin of the optic disc pit was noted. An unusual movement of this strand was observed during the surgery. The strand was excised, and fluid–gas exchange was performed using gas tamponade with 20% SF₆. After 12 months, a complete macular reattachment was obtained, with the VA improving to 1.2. Electron microscopic examination of the removed strand revealed abundant thick collagen fibrils with a frame of fine fibrils.Conclusion The unusual posterior vitreous strand connected to the optic disc pit may have contributed to the pathogenesis of maculopathy in this young child. Jpn J Ophthalmol 2005;49:264–266 © Japanese Ophthalmological Society 2005