Effect of Light Intensity on the Relative Afferent Pupillary Defect in Unilateral Neuro-ophthalmic Pathology.

SIGNIFICANCE: Objective pupillometry with standardized light intensities allows a comprehensive assessment of the relative afferent pupillary defect in patients with unilateral neuro-ophthalmic pathology. PURPOSE: This study aimed to determine the impact of varying light intensities on the grade of relative afferent pupillary defect in unilateral neuro-ophthalmic pathology vis-à-vis healthy controls. METHODS: Monocular pupillary light reflexes of 20 controls (14 to 50 years) and 31 cases (12 to 72 years) with clinically diagnosed relative afferent pupillary defect were measured thrice using 1-second-long light pulses, followed by 3 seconds of darkness, at eight light intensities (6.4 to 1200 lux) using objective pupillometry. The relative afferent pupillary defect was quantified as the ratio of the percentage change in the direct light reflexes of the left and right eyes. Its change with light intensity was described using standard exponential fits. RESULTS: The median (25th to 75th interquartile range) defect score of 54.8% cases decreased from baseline values of 1.58 (1.25 to 1.87) for right eye pathology and 0.45 (0.39 to 0.55) for left eye pathology to saturation values of 1.18 (1.05 to 1.31) and 0.98 (0.95 to 1.06), respectively, at light intensities between 56.9 and 300.5 lux. Like controls (1.01 [1.00 to 1.06]), the defect scores of the remaining 45.2% cases were constant with light intensity at 1.23 (1.18 to 1.46) and 0.87 (0.86 to 0.89) for right and left eye pathologies, respectively. CONCLUSIONS: Relative afferent pupillary defects may decrease with test light intensity in a significant proportion of patients with unilateral neuro-ophthalmic pathology. This highlights the importance of objective pupillometry with standardization light intensities for clinical assessment of afferent pupillary defects.

Splitting of retinal pigment epithelium and Bruch's membrane due to a focal choroidal excavation.

We report an unusual finding of a split between the Bruch's membrane (BM) and retinal pigment epithelium (RPE) due to a focal choroidal excavation (FCE) in a healthy young girl with sudden onset visual disturbance. She was followed up regularly for over a year with serial optical coherence tomography (OCT) scans which revealed a parafoveal conforming type of FCE. Initial retinal edema subsided in a month. No associated pathology, such as a choroidal neovascular membrane, was seen. A split was seen between the RPE and the BM on one side of the FCE, which remained unchanged. We postulate this novel finding of the split between the RPE and BM to be due to the inelasticity of the BM, causing it to separate from the RPE due to the sudden outward force exerted during the formation of an FCE.

Retinal perfusion density can predict cardiovascular disease risk in patients with retinal vein occlusion.

Purpose: To correlate microvascular changes and assess the relationship between microvascular changes and cardiovascular disease (CVD) risk in patients with retinal vein occlusion (RVO). Methods: Patients over 40 years of age with unilateral RVO were included in this prospective study. Those known to have cardiovascular disease were excluded. A detailed medical history was taken and physical exam was done to measure the height, weight, body mass index (BMI), and systolic blood pressure (SBP). A comprehensive eye check-up was followed by optical coherence tomography angiography (OCTA). Microvascular indices such as vessel density (VD) and perfusion density (PD) were noted. A statistical model was developed for prediction of CVD risk and was integrated with the World Health Organization (WHO)'s risk prediction charts. Results: This study included 42 patients with RVO and 22 controls with an age range of 42-82 years. There were 40 males (62.5%) and 24 females (37.5%). Along with age, SBP, and gender, perfusion density was found to have significant impact on CVD risk (P = 0.030). Reduction in PD was associated with increase in CVD risk. PD had a greater influence on CVD in <50 years age than in >70 years group. Using linear regression, a model with accuracy of 72.1% was developed for CVD risk prediction and was converted into color coded charts similar to WHO risk prediction charts. Conclusion: These findings suggest a significant correlation between microvascular parameters and CVD risk in RVO patients. Based on these parameters, an easy-to-use and color-coded risk prediction chart was developed.

Approach to inherited retinal diseases.

Inherited retinal diseases (IRDs) are a group of phenotypically diverse disorders with varied genetic mutations, which result in retinal degeneration leading to visual impairment. When a patient presents to a clinician who is not an IRD expert, establishing a correct diagnosis can be challenging. The patient and the family members are often anxious about further vision loss. They are eager to know the prognosis and chance of further worsening of the vision. It is important for every eye specialist to educate himself/herself about the basics of IRD. It would help to familiarize oneself about how to approach a patient with an IRD. An early and accurate diagnosis can help predict the vision loss and also help the patient plan his/her education and choose appropriate career choices. An updated knowledge about the genetic mutations, mode of inheritance, and possible therapies would empower the eye specialist to help his/her patients. This article gives a broad plan of how to approach a patient with IRD with regards to characterization and diagnosis of the disorder, visual rehabilitation, and possible therapy.

Structural and functional phenotypic features and molecular analysis of Indian patients with Bietti crystalline dystrophy.

Purpose: Bietti crystalline dystrophy (BCD) is a rare retinal dystrophy, uncommon in Indians. This study describes the various phenotypic features seen in the Indian population. Methods: In this retrospective, descriptive case series, records of patients with either clinical or molecular diagnosis of BCD from 2009 to 2020 were perused. Phenotypic and genotype information was collected and analyzed. Results: This study included 58 patients of BCD (31 males) aged 21-79 years (mean: 47 ± 14 years). The age at onset ranged from 7 to 41 years (mean: 28.8 ± 5.1 years). Vision ranged from 20/20 to counting fingers. There were 18 (31%) patients with stage 1 with crystals and mild retinochoroidal atrophy, 22 (38%) with stage 2 with atrophy extending beyond arcades, and 18 (31%) with absent crystals and extensive atrophy of stage 3. Choroidal neovascular membrane was seen in four patients. The optical coherence tomography showed retinochoroidal thinning (84.6%), outer retinal tubulations (71.8%), and paradoxical foveal thickening with interlaminar bridges (7.7%). Electrophysiology and visual fields showed reduced responses in advanced retinochoroidal changes. Molecular confirmation was available in five patients; five mutations were seen in the CYP4V2. Conclusion: A wide variation is seen in the phenotypic picture of BCD. A molecular diagnosis is helpful in differentiating from other retinal dystrophies. The OCT shows the peculiar feature of the interlaminar bridge in early cases with photoreceptor loss. Further investigations into this OCT feature may provide insights into the pathogenesis of BCD. A genotype-phenotype correlation could not be done.