EFFECTS OF TRANSIENT INDUCED ELEVATION OF THE INTRA-OCULAR PRESSURE ON THE VISUAL FIELD

[Changes in biomechanical properties of the ocular fibrous tunic in patients with primary open-angle glaucoma in response to drug-induced stress-relief tests]

AIM

To determine the effect of drug-induced stress-relief tests on biomechanical properties of the ocular fibrous tunic in eyes with early, moderate, or advanced primary open-angle glaucoma (POAG).

MATERIAL AND METHODS

A total of 202 eyes of 150 patients with POAG of different severity (early, moderate, or advanced) and 36 eyes of 30 healthy controls were examined. The mean patient age was 62±8.2 years. All groups were standardized by age, sex, and the range of corneal-compensated intraocular pressure (IOP) at baseline (21-30 mmHg). All patients underwent a standard ophthalmic examination, including visometry, biomicroscopy, gonioscopy, ophthalmoscopy, and Humphrey visual field assessment. Corneal hysteresis (CH), corneal resistance factor (CRF), CH-CRF difference, corneal-compensated IOP (IOPcc), and Goldmann-related IOP (IOPg) were measured with Ocular Response Analyzer (ORA, Reichert, USA). The axial eye length was measured on an ultrasonic A-scan (Ocuscan RxP, Alcon, USA) in the 10 MHz mode.

RESULTS

CH and CRF variability analysis was conducted to assess changes in biomechanical properties of the fibrous tunic due to an IOP decrease and a tendency toward compensation. For the first time, the ratio between CH and CRF changes (ΔCH/ΔCRF) was used to evaluate biomechanical properties of the fibrous tunic. This ratio provides understanding of the significance of CH and CRF changes after reduction of IOP. In early glaucoma patients, it differed inconsiderably from the control group (p>0.05) and averaged 1.62±0.9. In moderate glaucoma, CH changes were more pronounced than those of CRF: ΔCH/ΔCRF - 2.03±2.41 (under conservative treatment) and 2.12±1.07 (without treatment). In advanced glaucoma an opposite pattern was observed: the CH/CRF ratio got closer to 1.0 largely due to CRF changes, while CH changes became much less pronounced (or even negative, in some cases): ΔCH/ΔCRF - 0.27±0.32 (under conservative treatment), 0.16±1.29 (without treatment).

CONCLUSION

While the IOP decreased as a result of drug-induced stress-relief tests, CH and CRF changes differed between the groups depending on the stage of POAG. In early and moderate glaucoma, CH undergoes greater changes than CRF. In advanced glaucoma, CRF changes are more pronounced, and, hence, the ΔCH/ΔCRF ratio shifts reliably as glaucoma progresses. The ratio has also been shown to depend on the duration of the disease and on whether or not eye drops were prescribed.

Effect of prophylactic intraocular pressure-lowering medication (brinzolamide) on intraocular pressure after ranibizumab intravitreal injection: A case-control study

Purpose:

To observe the effect of prophylactic intraocular pressure (IOP)-lowering medication (brinzolamide) on IOP after ranibizumab intravitreal injections (IVIs).

Materials and Methods:

This prospective case–control study included 352 eyes from 352 patients (1 eye per patient) who were treated with ranibizumab intravitreal injection and divided randomly into two groups. Two hundred and three patients in control group only received the ranibizumab IVI, but 149 patients in case group received one drop of prophylactic intraocular brinzolamide preinjection. The IOP was measured by noncontact tonometer before injection, at 10, 30, 120 min and 1 day after injection in a sitting position.

Results:

The mean IOP measured before injection, at 10, 30, 120 min and 1 day after injection individually were 15.79 ± 2.21 mmHg, 19.33 ± 4.86 mmHg, 16.64 ± 2.93 mmHg, 16.17 ± 3.13 mmHg, and 15.07 ± 2.55 mmHg in case group and were 15.82 ± 2.57 mmHg, 21.34 ± 5.88 mmHg, 18.17 ± 4.06 mmHg, 17.59 ± 4.42 mmHg, and15.48 ± 2.92 mmHg in control group. Comparing two groups, the mean increase on IOP was statistically significant at 10, 30, 120 min postinjection (P < 0.05).

Conclusions:

IVI of ranibizumab causes a considerable short-term transient rise on IOP in most patients. The effect of prophylactic IOP-lowering medication on IOP after IVIs can be statistically significant from 10 min to 2 h after IVIs.

Effect of IOP on the visual field in ocuLar hypertension and glaucoma

The traditional opinion that increased intraocular pressure is the cause of glaucoma is controversial, probably mainly because of the fact that firm evidence for the value of pressure reduction is largely lacking. The present article reviews results from short term studies of visual fields before and after pressure reduction. It also reviews published and unpublished preliminary results from studies addressing the problem of whether the long term visual field prognosis, in glaucoma and in ocular hypertension, is affected by pressure lowering therapy. There is no convincing agreement among results from modern studies using computerized perimetry indicating that acute lowering of the ocular tension results in an improvement of the glaucomatous visual field. Long-term result are equally conflicting, and often negative. We have noted from a preliminary analysis of our own masked, prospective study of patients with 'high risk' ocular hypertension, that the same results may be interpreted in quite different ways. The results of available studies certainly indicate that pressure reduction does not automatically lead to clear and positive effects on the visual field. The studies have often been small, however, and have usually not had the power of detecting small effects of treatment. Also, pressure reduction has usually not been dramatic and many treated patients have maintained 'elevated' pressure levels. Patients with very high pressures have not been included, and the effect of pressure reduction in this situation has therefore not been investigated at all. More controlled, prospective therapeutic studies are necessary and ethical. It seems particularly important to study the long-term effects of non-pharmacologically induced pressure reduction in patients with manifest field loss.(ABSTRACT TRUNCATED AT 250 WORDS)

[Visual field response to hypotension following oculopression (author's transl)]

The authors studied the visual fields in 100 healthy persons of different ages before and 10 min after oculopression. They found a depression of the I/2 isopter mostly in the nasal lower quarter of the visual field in persons over 60 years old, due to a disturbed or diminished vascular compensation of bulbus compression. They consider that oculopression might have clinical importance as an indirect provocation test of the cellular blood circulatory system.

Flash perimetry

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