Clinical Significance of a Third or Fourth Anti-Glaucoma Eye Drop

Abstract

 

Purpose

 

To evaluate the effectiveness of a third or fourth topical anti-glaucoma medication in lowering intraocular pressure (IOP) and the probability of eventual glaucoma filtering surgery thereafter.

 

Methods

 

Glaucoma patients who had a third (Group A) or a fourth (Group B) anti-glaucoma eye drop added to their regimen were consecutively enrolled by reviewing medical records. Patients were required to have a prostaglandin analogue drop but no oral carbonic anhydrase inhibitor in their preexisting regimen and no prior filtering surgery. Fixed-combination eye drops were considered 2 different classes. IOP response to the added eye drop (‘pre-addition IOP’ - ‘post-addition IOP’; average of 3 IOP readings, respectively) was analyzed and the cumulative probability of filtering surgery, irrespective of subsequent IOP-lowering therapy (medication and/or laser), was calculated. Factors associated with IOP response and filtering surgery were identified.

 

Results

 

We included 83 eyes of 83 patients in Group A and 49 eyes of 49 patients in Group B. The mean baseline age was 71±10 and 72±14 years, respectively. IOP decreased significantly after adding a third (18.8±4.9 to 16.5±4.6 mmHg) or a fourth (19.6±6.6 to 17.6±5.3 mmHg) drop (all p<0.001). IOP response varied considerably, with 24% having IOP reduction >20% and 22-25% having IOP increase in both groups (Table 1). In a multivariable analysis, greater percent IOP reduction was significantly correlated with baseline IOP (p=0.001, R=0.356, Group A; p=0.037, R=0.306, Group B) and VF MD (p=0.022, R=−0.255, Group A; p=0.028, R=−0.321, Group B). The cumulative probability of filtering surgery was 18% at 1 year and 28% at 2 years in Group A and 27% at 1 year and 38% at 2 years in Group B (Fig 1). The median time to filtering surgery was 70 months (95% CI: 34-106 months) in Group A and 63 months (95% CI: 28-98 months) in Group B (p=0.24). Baseline IOP was a risk factor for eventual filtering surgery in both Groups A and B, and better VF MD and higher percent IOP reduction were protective factors in Group B (Table 2).

 

Conclusions

 

A third or fourth anti-glaucoma eye drop lowered IOP >20% in approximately one-fourth of patients. Approximately 3 to 4 of 10 patients would have a filtering surgery within 2 years after adding a third or a fourth eye drop. Baseline IOP and VF MD may affect IOP response to the added eye drop.

 

 

 

Keywords: 466 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • 568 intraocular pressure