Slit-lamp measurement of anterior chamber depth and its agreement with anterior segment optical coherence tomography and Lenstar LS 900 in pseudoexfoliation and normal eyes

Purpose: There is a considerable lack of awareness of slit-lamp measurement of anterior chamber depth (ACD) by the Redmond Smith method (SACD) in present day-to-day clinical practice, which may provide rapid assessment in pseudoexfoliation (PXF) when assessing for angle closure and planning for cataract surgery. This assumes importance not only in outreach clinics but also in the ongoing pandemic caused by the highly contagious novel coronavirus, where social distancing is advocated to contain the spread. We aimed to compare the axial ACD in PXF and normal patients by SACD, and its agreement with the anterior segment optical coherence tomography (ASOCT) and LenstarLS-900. Methods: A prospective comparative observational study was done at a tertiary eye care hospital. A PXF group and a normal group of controls were recruited. All eyes were phakic with normal cornea. Any eye with previous intraocular/refractive surgery and cause of other secondary or uncontrolled glaucoma was excluded. SACD was measured clinically via slit-lamp method and also via ASOCT and Lenstar; agreement between the methodologies was plotted. Results: Fifty patients were recruited in each group. Mean age was 66.82 +/- 4.88 years in PXF patients and 65 +/- 5.46 years in controls (P = 0.2). ACD was found to be greater in controls compared with the PXF patients; this difference was statistically significant (P < 0.001) across all methodologies. A good agreement with narrow 95% limits of agreement was found between these methodologies. Conclusion: Redmond Smith slit-lamp methodology of estimating the axial ACD is recommended as a rapid, quantifiable, noncontact screening technique during routine examination, especially in primary outreach centers, and is also advantageous during the ongoing pandemic by reducing expendable investigations.