Optical coherence tomographic features and correlation with visual acuity in adult-onset foveal vitelliform dystrophy

VP Indu; A Giridhar

doi:10.4103/kjo.kjo_50_17

ORIGINAL ARTICLE

Year : 2017 | Volume : 29 | Issue : 1 | Page : 14-17

Optical coherence tomographic features and correlation with visual acuity in adult-onset foveal vitelliform dystrophy

VP Indu, A Giridhar
Department of Vitreo Retina, Giridhar Eye Institute, Giridhar Eye Institute, Kochi, Kerala, India

Date of Web Publication

19-Jun-2017

Correspondence Address:
A Giridhar
Giridhar Eye Institute, Ponneth Temple Road, Kadavanthra, Kochi - 682 020, Kerala
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/kjo.kjo_50_17

Abstract

Purpose: The purpose of the study was to analyze the optical coherence tomographic (OCT) features of adult-onset foveal vitelliform dystrophy (AOFVD) using high-resolution spectral-domain (SD) OCT and to correlate each variable with visual acuity.
Design: This was a retrospective, observational case series.
Materials and Methods: Patients with a diagnosis of AOFVD based on clinical presentation, autofluorescence, and OCT were included in the study. SD-OCT images were analyzed. The vertical and horizontal basal dimensions of vitelliform material, the thickness of neurosensory retina (NSR) above the lesion, and the integrity of inner segment-outer segment (IS-OS) junction and external limiting membrane (ELM) were assessed, and each was correlated with best-corrected visual acuity.
Results: Thirty-six eyes of 25 patients were included in the study. Mean age of patients was 65.39 ± 11.3 years. A weak positive correlation was noted between lesion dimensions and LogMAR visual acuity, but this was not statistically significant. A significant negative correlation was seen between thickness of NSR above the lesion and LogMAR visual acuity, indicating that as the overlying NSR became thinner, vision worsened. Although a worse visual acuity was noted in eyes with disrupted IS-OS junction and ELM, the result was not statistically significant.
Conclusion: As the size of the vitelliform material increased, there was progressive thinning of overlying NSR which could lead to worsening of visual acuity.

Keywords: Adult-onset foveal vitelliform dystrophy, electrooculogram, inner segment-outer segment junction

How to cite this article:
Indu V P, Giridhar A. Optical coherence tomographic features and correlation with visual acuity in adult-onset foveal vitelliform dystrophy. Kerala J Ophthalmol 2017;29:14-7

How to cite this URL:
Indu V P, Giridhar A. Optical coherence tomographic features and correlation with visual acuity in adult-onset foveal vitelliform dystrophy. Kerala J Ophthalmol [serial online] 2017 [cited 2021 Jan 18];29:14-7. Available from: http://www.kjophthal.com/text.asp?2017/29/1/14/208488

Introduction

Adult onset foveal vitelliform dystrophy (AOFVD) is a relatively rare disease affecting the macula. The entity was first described by Gass in 1974.^[1] Onset of the disease is between the third and fifth decade of life.^[2],[3] The disease presents as unilateral or bilateral solitary, round or oval yellowish subretinal lesion, <1 disc diameter in size, and foveal or perifoveal in location with or without a central pigmented spot. Electrooculogram (EOG) is normal or mildly subnormal. Patients are usually asymptomatic or present with mild blurring of vision.^[3] Both heritable (autosomal dominant) and sporadic cases have been described.^[4] AOFVD differs from Best disease in that the former presents at a later age, with a smaller lesion and a normal EOG, while Best disease begins at a younger age with a much larger lesion and abnormal EOG in most cases.^[3]

The vitelliform material has been hypothesized to be composed of photoreceptor debris (lipofuscin) due to faulty phagocytosis, mixed with pigments from disrupted retinal pigment epithelium (RPE).^[5] It has been postulated that vitelliform material first accumulates between RPE and inner segment-outer segment (IS-OS) junction which is seen as high reflective dome-shaped lesion on optical coherence tomogram (OCT). Puche et al.^[6] described the IS-OS junction as forming a highly reflective shell around the vitelliform material. As there is a progressive accumulation of vitelliform material, it has been found to cause progressive thinning of neurosensory retina (NSR) above the lesion. Poor best-corrected visual acuity (BCVA) has been found to correlate with reduced thickness of NSR at the fovea.^[4],[7]

With time, the vitelliform material has been found to cause disruption of IS-OS junction. Pigments break through the IS-OS junction and external limiting membrane (ELM) and enter the outer plexiform and outer nuclear layers.^[6],[8] It has also been shown that vitelliform material undergoes fragmentation and disappears leaving behind an area of RPE atrophy.^[3] Loss of visual acuity has been correlated with disruption of ELM and IS-OS junction on OCT as well as collapse of the lesion with atrophy.^[9] Another cause of reduced visual acuity has been the development of choroidal neovascular membrane (CNVM).

The purpose of the study was to analyze the OCT features of AOFVD using high-resolution spectral-domain (SD) OCT and to correlate each variable with visual acuity.

Materials and Methods

Records of patients evaluated between December 2014 and February 2016 in our department with a diagnosis of AOFVD were screened. Patients included had to fulfill the following criteria – age more than 30 years at presentation, clinical appearance of solitary yellowish lesion at macula, hyperautofluorescence of the lesion, and OCT showing the typical dome-shaped hyperreflective lesion between RPE and IS-OS junction [Figure 1].

Figure 1: Yellowish vitelliform lesion at the fovea in the left eye. The lesion is hyperautofluorescent. Optical coherence tomographic image through the center of fovea showing deposition of hyperreflective material between retinal pigment epithelium and photoreceptor layer

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All patients had undergone complete ophthalmological evaluation including BCVA with Snellen charts (and later converted to LogMAR), fundus examination, autofluorescence, and SD-OCT. Fluorescein angiography and EOG were not considered necessary for diagnosis. Exclusion criteria included the presence of CNVM or any other macular diseases such as diabetic retinopathy, epiretinal membrane, or age-related macular degeneration. OCT images were acquired with spectralis HRA-OCT (Heidelberg Engineering, Heidelberg, Germany). Horizontal scan through the center of the fovea and vitelliform material was considered. Horizontal diameter of the lesion was taken from either edge of the lesion [Figure 2]. The vertical height was taken from the apex of the lesion to the RPE [Figure 2]. The integrity of IS-OS junction and ELM was assessed and grouped as intact or disrupted [Figure 3]. The thickness of neurosensory retina above the lesion was measured from the internal limiting membrane of center of fovea perpendicularly down to the apex of the lesion [Figure 2]. First available OCT scan of each patient was considered for the study. The variables horizontal diameter and vertical height of the lesion, thickness of NSR, and integrity of ELM and IS-OS interface were correlated with LogMAR BCVA. Statistical analysis was done using SPSS version 16 (SPSS Inc., Chicago, IL, USA). Spearman's correlation was used. P< 0.05 was considered statistically significant.

Figure 2: Measurement of vertical and horizontal dimensions of the lesion (black line) and thickness of neurosensory retina above the lesion (yellow line)

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Figure 3: (a) Vitelliform material with intact inner segment-outer segment junction and external limiting membrane, (b) vitelliform material causing disruption of inner segment-outer segment junction and external limiting membrane, (c) intact external limiting membrane with disruption of inner segment-outer segment junction, (d) disruption of inner segment-outer segment junction and migration of pigments to outer plexiform layer

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Results

Thirty-six eyes of 25 patients were included in the study. Age at presentation ranged from 42 to 83 years, with a mean of 65.39 ± 11.35 years. About 44.4% were males and 55.6% were females. Fourteen patients had unilateral disease, and 11 patients had bilateral disease. BCVA ranged from 6/6 to 6/60. Nearly 58.33% patients had BCVA better than or equal to 6/9 [Table 1].

Table 1: Best-corrected visual acuity (Snellen chart) and its distribution among patients

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Lesion height ranged from 71 to 247 μ, with a mean of 127 μ. Horizontal diameter ranged from 279 to 1520 μ, with a mean of 742.16 μ. Lesion height and horizontal diameter of the lesion were found to have a weak positive correlation with BCVA. However, the result was not statistically significant [Table 2].

Table 2: Correlation between LogMAR best-corrected visual acuity and lesion dimensions/neurosensory retina thickness

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Thickness of NSR ranged from 43 to 167 μ, with a mean of 87.36 μ. There was a moderate negative correlation between LogMAR visual acuity and thickness of NSR (correlation coefficient: −0.39) which was statistically significant (P = 0.01), i.e., as NSR became thinner, BCVA reduced [Table 2] and[Table 3].

Table 3: Correlation between LogMAR best-corrected visual acuity and thickness of neurosensory retina

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IS-OS junction was intact in six eyes and disrupted in thirty eyes. Mean LogMAR visual acuity in intact eyes was 0.21 ± 0.14 and in disrupted eyes was 0.33 ± 0.24; however, the difference was not statistically significant.

Twenty-three eyes had an intact ELM and 13 eyes had disrupted ELM. Mean visual acuity in intact ELM was 0.28 ± 0.18 and in disrupted eyes was 0.36 ± 0.30; however, the difference was not statistically significant.

Discussion

Main goal of the study was to assess the morphological features of AOFVD on SD-OCT and to assess their correlation with visual acuity. More than 50% of patients in this study had BCVA better than 6/9 which was in agreement with most other studies.

Lesion height and horizontal dimension of the lesion showed a weak positive correlation with LogMAR visual acuity, indicating that as the size of the lesion increased, there was reduction in BCVA. Furthermore, the thickness of NSR showed a moderate negative correlation with LogMAR visual acuity which implied that as NSR became thinner, there was a progressive reduction in visual acuity and this was found to be statistically significant. These findings are in agreement to the previous studies which have shown that as lesion size increased, there was progressive thinning of overlying retina. This thinning of NSR has been associated with poor visual acuity as shown in other studies.

Disruption of ELM and IS-OS junction has been documented to cause worsening of visual acuity. In this study, BCVA was found to be worse in eyes with disrupted ELM and IS-OS junction as compared to intact ELM and IS-OS junction, but this was not statistically significant.

Conclusion

We postulate that size of the lesion, thickness of NSR above the lesion, and integrity of IS-OS junction and ELM are important determinants of visual acuity in patients with AOFVD.

This study has various limitations. Most importantly, sample size was small, AOFVD being a relatively rare disease. Furthermore, longitudinal observations over long periods of time would help understand the disease better. Third, choroidal thickness was not considered as a variable for the present study. There are various studies which demonstrate an increase in choroidal thickness in AOFVD. Hence, assessment of choroidal features in AOFVD would give more insight into the pathogenesis and natural course of the disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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