Abstract
BackgroundTo evaluate depth perception in Primary open angle glaucoma (POAG), glaucoma suspects compared to controls and to determine the association between depth perception and severity of glaucoma.MethodsThis was a hospital based, comparative, cross-sectional study. The ethical clearance was taken from institutional review committee of Institute of Medicine [Reference no.399 (6–11) E2 077-078]. Agematched, equal number of participants in each group (N=20) were evaluated with both Titmus and Frisby stereoacuity tests to measure depth perception as stereopsis threshold in seconds of arc. The participants were selected using the purposive sampling technique.ResultsThere was no differences in age, sex, or best corrected visual acuity, intraocular pressure, central corneal thickness (CCT), found among the three groups (POAG, Glaucoma Suspects and Control) respectively. However, there was significant difference in cup disc ratio (CDR) between the groups. Equal number of male and female were there in each group, while in POAG group male to female ratio was 3:2. The mean stereoacuity threshold in control group was 53.5±23.23 seconds of arc with Titmus test and 38.75±18.83 seconds of arc with Frisby stereoacuity test. The difference in threshold was significant between control and glaucoma suspect with Titmus (t=1.991, p=0.05) and with Frisby (t=2.114, p=0.04). The difference was also significant in POAG group by Titmus (t=3.135, p=0.0033) and by Frisby (t=3.014, p=0.004). More so, with increasing severity of glaucoma, the mean threshold of stereopsis increased as seen with both Titmus and Frisby Tests (ANOVA, p < 0.001)ConclusionPrimary open angle glaucoma patients and glaucoma suspects, showed significant reduction in depth perception. Decreased stereoacuity was associated with greater glaucomatous visual field loss.
Highlights
Glaucoma is a progressive optic neuropathy which leads to irreversible functional loss of vision
This study showed that stereoacuity was reduced among glaucoma and suspects compared to control and this increase in the threshold correlated with disease severity
We found that Primary open angle glaucoma patients and glaucoma suspects, showed significant reduction in depth perception measured with both Titmus and Frisby Depth Test, which may have utility in identifying early glaucomatous nerve damage
Summary
Glaucoma is a progressive optic neuropathy which leads to irreversible functional loss of vision. Perimetry is the standardized tool for assessing glaucoma progression since visual field loss is the most common form of functional vision loss associated with glaucoma [1]. The progressive loss of RGC in patients with glaucoma can be correlated with decreased depth perception seen in glaucoma. This structural basis of stereoacuity deficits was explored in one study and found that with decrease in RNFL thickness, Adhikari et al BMC Ophthalmology (2021) 21:432 stereoacuity both for distance and near decreases [7]. There have been very few studies, which have evaluated stereoacuity as a part of functional impairment in glaucoma. Depth perception deficit may precede visual field loss in glaucoma [5]. To evaluate depth perception in Primary open angle glaucoma (POAG), glaucoma suspects compared to controls and to determine the association between depth perception and severity of glaucoma
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