A NEW COMPUTER-ASSISTED OBJECTIVE METHOD FOR QUANTIFYING VASCULAR CHANGES OF THE BULBAR CONJUNCTIVAE

A novel computer software method was used to quantify the conjunctival plexus on the scleral background for measurement of the vascular surf ace area from photographs. A previously described method was used (Pal mer, J. R., Owen, C. G., Ford, A. M., Jacobson, R. E. and Woodward, E. G. (1996). Optimal photographic imaging of the bulbar conjunctival va sculature. Ophthal. Physiol. Opt. 16, 144-149) to optimise photographi c imaging of the bulbar conjunctival vasculature by increasing the inf ormation content in the image. Repeatability of this technique was eva luated. Twenty subjects (20 eyes) free from ophthalmological and syste mic abnormality were examined on two separate occasions. The maximum 9 5% confidence limits for repeatability are +8.58/-3.95%. For 10 consec utive estimates of vascularity the maximum 95% confidence interval lie between +/-6.54%. To evaluate the technique the lateral-bulbar conjun ctivaein 10 soft (SCL) and 10 rigid gas permeable contact lens (RGPCL) wearers during the first 10 months of contact lens wear, were assesse d and compared with subjective grading of hyperaemia. The new method s howed sufficient sensitivity in detecting increased hyperaemia in the RGPCL wearing group and demonstrated statistically significant change. Subjective graded assessment of vascularity (using established classi fications) detected increased hyperaemia, however, this was not statis tically significant. Conjunctival vasculature is a dynamic structure a nd a source of valuable quantitative information where the ocular envi ronment is varied, or where the ocular surface is affected by disease. Hence it is worthy of further investigation. A simple inexpensive met hod of computer assisted determination of vascularity is described. Co pyright (C) 1996 The College of Optometrists.