Toxoplasmosis retinochoroiditis and elevated intraocular pressure: a retrospective study

To report the prevalence of abnormal intraocular pressure (IOP) in patients with toxoplasmosis retinochoroiditis and to determine risk factors for such abnormality.

In a retrospective clinic-based chart review, the IOP levels of 61 patients with active retinochoroiditis were recorded. Patients were separated into groups with elevated IOP, equal IOP, and lower IOP. The time taken for normalization of IOP was also recorded. Additionally, age, gender, visual acuity, anterior chamber and vitreous inflammatory activity, presence of macular lesions, keratoprecipitates, synechiae, toxoplasmosis antibody titers, and required medical and surgical treatments were noted. The IOP in 61 patients with active retinochoroiditis were also compared with the IOP in 59 age- and gender-matched control patients with unilateral anterior uveitis.

Thirty-eight percent of patients (23/61) with active retinochoroiditis had elevated IOP > 21 mm Hg, demonstrated IOP difference > 4 mm Hg between involved and uninvolved eyes, or received on IOP-lowering medications. In the equal IOP category, 55.7% (34/61) of patients had an IOP < or = 21 mm Hg in the actively inflamed eye and had an IOP difference of < or = 3 mm Hg between the active and inactive eyes. Only 6.6% (4/61) of patients with active ocular toxoplasmosis had a decreased IOP in the affected eye. The mean IOP in patients with active retinochoroiditis was 21.2 mm Hg (SD 11.5) and 15.6 mm Hg (SD 2.9) in involved and uninvolved eyes, respectively. A statistically significant average IOP difference of 5.8 mm Hg (SD 11.6) was found between the involved and uninvolved eyes (P < 0.001 by two-tailed student T test). Of the patients with abnormal IOP, 20 patients had IOP > 21 mm Hg, 10 of whom had IOP > 30 mm Hg, 6 of whom had IOP > 40 mm Hg, and 2 of whom had IOP > 50 mm Hg. In the elevated IOP group, the average time from onset of symptoms until presentation for their IOP measurement was 13 days (median: 7 days; range: 1 to 100) with resolution of abnormal IOP occurring in 32 days (median: 28 days; range: 1 to 84 days). The average time of onset of symptoms in the normal to low IOP category was 70 days (median: 17.5 days; range: 2 to 330 days). Elevated IOP was more common in active retinochoroiditis, 23/61 (38%), when compared with anterior uveitis control group, 6/59 (10%) (odds ratio of 5.3; P < 0.001). No statistically significant predictor of elevated IOP was identified, though a trend associating anterior chamber cells with elevated IOP (P = 0.08, r = 0.25 Spearman rank correlation coefficient) was seen.

Abnormal IOP is a feature in almost half of patients with active toxoplasmosis retinochoroiditis. Elevated IOP occurs in 38% and low IOP occurs in 6.6% of affected eyes. Patients with elevated IOP due to active toxoplasmosis present for earlier evaluation than patients with normal or low IOP. The IOP elevation is generally transient and concurs with the uveitic episode. Medical management of IOP is usually sufficient to treat this generally transient eye pressure rise though chronic administration of eye pressure lowering drops or glaucoma surgery may be necessary in a small proportion of patients.