Evaluation of depth perception and association of severity in Glaucoma patients and suspects

Abstract

Background 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. Methods This 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. Results There 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) Conclusion Primary open angle glaucoma patients and glaucoma suspects, showed significant reduction in depth perception. Decreased stereoacuity was associated with greater glaucomatous visual field loss.

Extraction of three-dimensional shapes in glaucoma patients in response to monocular depth cues

“…The same visual stimuli and task procedures were also used to test patients with strabismus, and increased error-in-depth values for 3D-SfS were associated with a lack of binocular stereopsis [ 16 ]. Therefore, the larger thresholds observed for 3D-SfS in this study could be attributed to impaired binocular depth perception, which is also observed in glaucoma [ 8 , 9 ]. However, compared with the strabismus patients, those with glaucoma were less able to distinguish the brightness of luminance.…”

“…The binocular depth perception of individuals with confirmed or suspected glaucoma is impaired due to disruption of binocular interactions [ 8 , 9 ]. Depth structure is impaired but can still be perceived; pictorial monocular depth cues, such as shading and texture, and monocular motion parallax cues contribute to this capability [ 10 – 12 ].…”