The influence of central corneal thickness on progression of normotensive glaucoma

To verify whether there is a relation between central corneal thickness (CCT) and progression of normotensive glaucoma (NTG), to assess the impact of early changes in the visual field on their progression in time.

The sample consisted of two groups of patients with NTG. In the first group there were 50 eyes of 25 persons (15 females and 10 males) average age 63 years who had been treated with prostaglandins. The second group consisted of 50 eyes of 25 persons (16 females and 9 males) average age of 62 years who had had no local therapy. All patients were cardiologically compensated and had no other internal or neurological disease. Visual acuity was 1.0 with a possible correction (less than ±3 dioptres) in all patients. The IOP ranged between 10-15 mmHg in all patients. If hypotensive ophthalmological therapy was initiated, it had been stable for the last five years. In all patients, we monitored CCT, excavation in the papilla (c/d), pattern defect (PD) and overall defect (OD) of the visual field. In 2013, changes in the visual fields were approximately the same in all patients. We compared the results of the visual fields after five years, i.e. the results were obtained in 2018. CCT was measured, using the ultrasound pachymeter Tomey SP-100. PD and OD of the visual field using the glaucoma fast threshold program with the MEDMONT M 700 device. For statistical comparison, we used the paired t test and correlation analysis.

In both groups, we found progression of PD in time (P=0.0000, P=0.0001, respectively). In the patients treated with prostaglandins, OD had not statistically significantly changed (P=0.49) in contrast to the untreated patients (P=0.001). There was no statistically significant relation between CCT and PD in any of the groups. It was similar between the CCT and OD. In the treated NTG patients, we found a weak correlation between the changes in PD in time (r=0.2846, P=0.0438) and moderately strong relation for OD (r=-0.63). The finding was similar in untreated patients PD (r=-0.2, P=0.162) and OD (r=-0.443, P=0.001).

We found no relationship between progression of changes in the visual fields in CCT. Progression of changes in the visual fields was higher in patients who had more advanced changes at the beginning of observation. The untreated patients had progression of changes in the visual fields both in PD and OD in contrast to those who were taking prostaglandins and presented changes only in PD.