Inter-eye asymmetry of intraocular pressure is a common finding in patients with glaucoma; there is a direct relationship between the amount of IOP asymmetry between fellow eyes and the likelihood of having glaucoma.

In a collaborative, retrospective study, former Wills Eye Institute fellows collected single pretreatment measurements of IOP on patients diagnosed as having definite glaucoma (n=326) based on characteristic optic nerve damage and confirmatory visual field damage. Controls were patients with a normal eye examination (n=326) who had normal-appearing optic discs and no apparent glaucoma, or a normal eye examination in association with refractive error or cataract.

Intraocular pressure asymmetry is a risk factor for having glaucoma (risk: 2.14; 95 percent CI, 1.86-2.47; p<0.001). Absence of IOP asymmetry between the fellow eyes is associated with a 1 percent probability of having glaucoma. A difference of 3 mmHg is associated with a 6 percent probability and a difference of >6 mmHg with a 57 percent probability of having glaucoma. The association between IOP asymmetry and glaucoma status is significant for subjects with both elevated IOP (p=0.014) and statistically normal IOP (maximum IOP ≤21 mmHg; p<0.001).

An interventional prospective study from the Lounceston Eye Institute in Tasmania concludes that femtosecond laser pretreatment is associated with a mean peak increase in intraocular pressure of 18.5 mmHg from baseline and appears to be safe and well-tolerated.

Femtosecond laser pretreatment was performed using the Catalys Precision Laser System with Liquid Optics Interface. The IOP was measured using an iCare PRO rebound tonometer during different stages of surgery and analyzed by number of docking attempts, vacuum time, treatment time and central corneal thickness.

The mean baseline IOP in the 25 study eyes was 17.5 ±2.5 mmHg. During vacuum application, the mean IOP rise was 11.4 ±3.3 mmHg. Peak IOPs were recorded immediately after laser capsulotomy and lens fragmentation (mean: 36.0 ±4.4 mmHg; mean increase from baseline 18.5 mmHg) and remained above baseline two minutes after the procedure (26.6 ±4.0 mmHg; p<0.001). Multiple regression analysis found no association between IOP rise and number of docking attempts, vacuum time, treatment time or CCT.

Changes in PEDs a Predictor for Anti-VEGF Retreatment

Research from the Bascom Palmer Eye Institute suggests that quantitation of the change in retinal pigment epithelial detachment volume and area may be useful in determining when to retreat eyes undergoing spectral domain optical coherence tomography-guided, as-needed, anti-vascular endothelial growth factor therapy.

Fourteen eyes from 14 patients with vascularized PEDs undergoing SD-OCT treatment with anti-VEGF drugs were retrospectively identified. The decision to retreat these cases was based on qualitative assessments of fluid in the macula. SD-OCT images from visits in which treatment was withheld were retrospectively analyzed, and a novel algorithm was used to measure the area and volume of PEDs at these visits.

Retreatment was withheld at 57 visits. When the SD-OCT algorithm was used to evaluate the scans from these visits, the PED volume increased at eight visits. At all of these eight visits, a treatment was needed at the next follow-up visit. For the remaining 49 visits in which treatment was withheld, the PED volume did not increase and no treatment was needed at the next follow-up visit.