Reply: Intraocular pressure spike prophylaxis in glaucoma patients 1 day after phacoemulsification

Abstract

Drs. Gupta and Vernon emphasize the need for better studies to inform the recommendations for postsurgical management of the glaucoma patient having cataract surgery. We agree that this subject is important, not only to guide system-wide recommendations, but also to provide the best surgical outcomes for patients who have preexisting vision loss from glaucoma. In addition, we appreciate their comments regarding our chosen definition of IOP spike. We considered several different criteria, but as noted in the paper, chose percentile change from baseline to reflect general conventions in IOP-lowering guidelines. During the data analysis, we statistically examined different definitions of an IOP spike, including IOP elevation greater than 10 mm Hg above baseline, but did not detect a meaningful difference from the percentile change (data not shown). We did not consider an absolute number (ie, >30 mm Hg) for a definition as we felt that a postoperative IOP in the mid to upper 20s in patients with a preoperative IOP in the single digits or low double digits would be considered clinically relevant and likely to prompt additional therapy or monitoring. One important gap in our knowledge is the effect of acute IOP elevation on the visual field of patients with and without field loss. There are reports of acute visual field loss associated with short-term IOP spikes in patients having laser trabeculoplasty,1 as well as in patients who have an attack of acute angle closure.2 Another paper failed to detect a change in visual field loss in patients who had an IOP spike after trabeculectomy.3 Presumably, patients with the most severe visual field loss would be at highest risk for losing vision after an acute IOP spike, as proposed by some authors.4 On the other hand, given the frequency of cataract surgery in glaucoma patients, the lack of even anecdotal evidence suggesting that a subset of patients have significant vision loss after cataract surgery should be reassuring. As Drs. Gupta and Vernon note, additional information is needed before firm guidelines about adequate monitoring of post-cataract-extraction IOP in the patient with preexisting glaucoma can be issued. Consideration should be given to the preoperative level of IOP, number of medications, and prior laser or glaucoma surgeries. In addition, we would suggest that preoperative visual fields be carefully examined and extra precautions taken with patients who have more advanced visual field loss or paracentral and “fixation splitting” field loss.