Purchase this article with an account.
Prema Padmanabhan, Sushmitha Dandapani, Jameel Rizwana Hussaindeen; Spectrum of Binocular Vision Function in Keratoconus Patients. Invest. Ophthalmol. Vis. Sci. 2019;60(9):338.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Keratoconus(KC) is a bilateral, asymmetric corneal ectasia that causes progressively increasing refractive errors, higher order aberrations and visual impairment, all of which could impact binocular vision(BV). However, this aspect of visual performance has not been adequately reported. This study aims at measuring various parameters of BV in patients with KC and identifying factors that possibly influence them.
This was a prospective, case-controlled study of BV in patients diagnosed with KC, without manifest squint and best corrected visual acuity(BCVA) ≥ 0.4 logMAR in each eye. Age-and sex-matched, non-strabismic patients served as controls. With an informed consent, all patients underwent comprehensive ocular examination including objective and subjective refraction, sensory and motor assessment, accommodation parameters (accommodative amplitudes and facility), fusional vergence (near point of convergence, vergence amplitude for distance and near and vergence facility). Statistical analysis was performed using SPSS version 14.
BV parameters of 84 KC patients were compared with those of 71 normal controls. The KC group showed statistically significant differences between fellow eyes in refractive cylinder(0.44±2.1D, p=0.03), BCVA(0.06±0.09 logMAR p=0.001) and Kmax(6.64±8.16D, p=0.005). The control group showed no significant difference in any refractive or keratometric parameter between fellow eyes. 66 of 84 (78.6%) KC patients had various combinations of BV anomalies:47.61% had impaired stereopsis, 44% had abnormal fusional vergence, 39.3% had accommodative infacility. Among individual parameters, all except accommodative amplitudes and negative distance fusional vergence showed statistically significant impairment compared to controls (p<0.001). Mean stereoacuity was 391±228.8 arc sec in the KC group and 43.5±15.6 arc sec in control (p<0.0001). There was a statistically significant but weak correlation between difference in Kmax between fellow eyes and stereoacuity (p=0.009, Pearson coefficent 0.28). There was a statistically significant but weak correlation between fusional vergence and stereoacuity (p=0.005, Pearson coefficient -0.22).
Our study confirms that a large proportion of patients with KC have non-strabismic BV anomalies. Assessment of BV should be included in the clinical examination of all patients and appropriate management should be incorporated in the treatment protocol of KC.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
This PDF is available to Subscribers Only