Comparison of visual acuity measurements and Purkinje's vessel shadow perception for prediction of postoperative visual acuity in different ophthalmological diseases

Purpose: Prediction of postoperative visual acuity (VA) is extremely important to the patient and highly relevant to the surgeon. However, objective evaluation of the macula is frequently impossible in cases such as mature cataract, cataract in high myopia or vitreous haemorrhage. This study compares different preoperative examination techniques used to predict postoperative VA. Methods: We retrospectively evaluated the charts of all patients who underwent any of the following procedures at our hospital in 2004: phacoemulsification for mature cataract or cataract in high myopia; vitrectomy for diabetic vitreous haemorrhage; macular pucker, and macular hole. The following methods were evaluated: preoperative distance and reading VA; laser interferential VA; Purkinje's vessel shadow perception, and postoperative distance VA. Results: Complete documentation was available for 136 patients (29 mature cataracts, 25 immature cataracts in high myopia, 42 vitreous haemorrhages, 19 macular puckers, 21 macular holes). In cases of preoperative mature cataract, a positive Purkinje's vessel shadow perception predicted a postoperative VA >= 20/50 (odds ratio 11.2). In cases of high myopia, interferential VA correlated best with visual outcome (p < 0.05). In macular surgery laser interferential VA predicted postoperative VA to be better and preoperative reading VA predicted it to be worse than it actually turned out after surgery. Laser interferential VA and last known VA prior to vitreous haemorrhage (mean of 20 months previously) correlated best with postoperative VA (p < 0.05) in cases of vitreous haemorrhage. Purkinje's vessel shadow perception - if positive - predicted a postoperative VA >= 20/300 in these cases (odds ratio 15.0). Conclusions: Postoperative VA after vitrectomy for macular pucker or macular hole and in cases of cataract in high myopia is best predicted by laser interferential VA. Postoperative VA after vitrectomy for diabetic vitreous haemorrhage is best predicted by prehaemorrhage VA or laser interferential VA, especially when prehaemorrhage VA is unknown. Positive Purkinje's vessel shadow perception is an excellent method of predicting postoperative VA >= 20/300 in cases of vitreous haemorrhage and VA = 20/50 in mature cataract.