Clinical applications of the retinal functional imager: A brief review

The advances in treating blinding conditions often depends on the development of new techniques that allows early detection, treatment, and follow-up of the disease. Functional changes often precede structural changes in many retinal disorders. Therefore, detecting these changes helps in early diagnosis and management, with the intention of preventing permanent morbidity. The Retinal Functional Imager (RFI) is a non-invasive imaging system that allows us to assess the various functional parameters of the retina. The RFI quantitatively measures the retinal blood-flow velocity, oxygen saturation, metabolic demand and generates a non-invasive capillary perfusion map that provides details similar to a fluorescein angiography. All of these parameters correlate with the health of the retina, and are known to get deranged in retinal disease. This article is a brief review of published literature on the clinical utility of the RFI.

Morphometric analysis of retinal arterioles in control and hypertensive population using adaptive optics imaging

Purpose: To measure the wall-to-lumen ratio (WLR) and the vascular wall cross-sectional area (WCSA) of retinal arterioles by an Adaptive Optics (AO) retinal camera using semi-automated software and comparing them between control and hypertensive population. Methods: This was a cross-sectional observational study including a hypertensive group and a control group. Subjects were examined and their medical history recorded. Retinal arteriolar morphometry was assessed by rtx1 AO retinal camera using AOdetect Artery semiautomated software. Main Outcome Measures: WLR and WCSA were measured on the basis of retinal arteriolar wall thickness (W1, W2), lumen diameter (LD) and vessel diameter (VD). Influence of age and arterial hypertension on the WLR and WCSA were examined. Results: A total of 150 human subjects were included out of which 110 were controls and 40 were hypertensives under treatment. There was statistically significant difference in the age, systolic and diastolic blood pressures between the control and hypertensive groups (P < 0.01). We found no significant correlation between age and WLR (R2 = 0.049, P > 0.05) or age and WCSA (R2 = 0.045, P > 0.05). We observed a significant difference in WLR and WCSA measurements between control and hypertensive groups (P < 0.01). On measuring intra-observer variability (IOV) we found excellent consistency. Conclusion: AO retinal imaging allows a direct measurement of the retinal vessel wall and LD with excellent IOV. WLR and WCSA reflect the remodelling process and can be used to further aid the early detection and monitoring of systemic hypertension.

Retinal immaturity at first screening and retinopathy of prematurity: Image-based validation of 1202 eyes of premature infants to predict disease progression

Purpose: To use the extent of retinal immaturity at the first visit to predict progression to any stage and treatment-requiring retinopathy of prematurity (ROP). Methods: Retrospective, multicenter, nonrandomized, observational, clinical, validation study. In all, 601 Asian Indian preterm infants born < 2000 g and/or < 34 weeks of gestation completing ROP screening with RetCam images taken during each visit were included. A total of 1202 eyes of these infants were classified into three groups based on the retinal immaturity at the first screening visit into “mild” (Group 1), vessels reaching the posterior boundary of zone 3; “moderate” (Group 2), vessels entering zone 2 anterior; and “severe” (Group 3), vessels in zone 1 or zone 2 posterior. RetCam images at each subsequent visit were evaluated and the proportion of eyes that progressed to Type 1 or Type 2 ROP was correlated with the degree of retinal immaturity. Results: Of the 958 eyes in Group 1, 200 eyes in Group 2, and 44 eyes in Group 3, any stage ROP developed in 15% of eyes in Group 1, 46.5% of eyes in Group 2, and 100% of eyes in Group 3 (P < 0.001). Sixteen of 128 eyes (12.5%), 12 of 72 (16.6%), and 28 of 44 of eyes (63.6%) in Groups 1, 2, and 3, respectively, required treatment (P < 0.001). Conclusion: Retinal immaturity at first screening visit predicts Type 1 and Type 2 ROP. “Severe” immaturity is more likely to progress to “treatment-requiring” disease. This could be a useful tool for prognostication, counseling, and scheduling follow-up.

Bilateral combined central retinal artery and vein occlusion in a 3-year-old child with nephrotic syndrome

Nephrotic syndrome (NS) is a common disease of childhood but ophthalmic manifestations are seldom reported. We report a rare occurrence of bilateral combined central retinal artery and vein occlusion in a 3-year-old with NS. The child presented with bilateral painless loss of vision, central pallid retinae with cherry red spots, vascular tortuosity, and retinal hemorrhages. There was delayed filling of the arteriolar circulation and a delay in arteriovenous transit time on angiography and increased central retinal thickening on optical coherence tomography. She was treated with oral steroids, subcutaneous low molecular weight heparin, and oral acetylsalicylic acid. The central retinae showed resolution of the hemorrhages, tortuosity, edema, and pallor within 3 weeks. Visual acuity recovered bilaterally to 20/360, 20/190, and 20/40 at 1, 3, and 6 weeks, respectively. We discuss the possible reasons for good recovery in our patient. Though bilateral combined central retinal artery and vein occlusion is rare in pediatric NS, the treating physician should be aware of this entity as it can be successfully managed.