Recovery of corneal hysteresis after reduction of intraocular pressure in chronic primary angle-closure glaucoma.

PURPOSE: To measure corneal hysteresis (CH) in unilateral chronic primary angle-closure glaucoma (CPACG) patients to determine if it was affected by high intraocular pressure (IOP). DESIGN: Prospective interventional case series. METHODS: CH and Goldmann-correlated IOP (IOPg) were obtained with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Dephew, New York, USA) and central corneal thickness (CCT) was measured by optical coherence tomography. Baseline CH, IOPg, and CCT were measured in 40 CPACG eyes and compared to the fellow eyes and 40 normal controls. Reduction of IOPg in CPACG eyes was achieved medically, followed by trabeculectomy and peripheral iridectomy. Measurements were repeated at 2 and 4 weeks posttherapy. RESULTS: IOPg decreased significantly from 31.55 +/- 10.48 mm Hg (mean +/- standard deviation) before therapy to 11.47 +/- 4.71 mm Hg, and CH increased significantly from 6.83 +/- 2.08 mm Hg to 9.22 +/- 1.80 mm Hg at 2 weeks, with no further changes after that. However, the CH in the treated eyes remained significantly lower compared with that of fellow and normal eyes. Before treatment, CH was negatively correlated with IOPg; however, there was no correlation after treatment. CCT was not affected by the reduced IOPg in the CPACG eyes. CONCLUSIONS: CH was significantly lower in CPACG patients, and partial recovery occurred after successful IOP-lowering therapy. Alternations affecting corneal biomechanical properties appear to occur during glaucoma development.

Diurnal variation of ocular hysteresis, corneal thickness, and intraocular pressure.

PURPOSE: To investigate, in healthy Asian subjects, the diurnal changes of the corneal biomechanical properties of corneal hysteresis (CH) and its relation to fluctuations of intraocular pressure (IOP) and central corneal thickness (CCT) after sleeping. METHODS: Forty eyes of 20 healthy Asian volunteers (4 males and 16 females) with a mean age of 19.7 +/- 1.1 years were measured with a modified retinal optical coherence tomography and an ocular response analyzer (ORA). CH, CCT, Goldmann-equivalent intraocular pressure (IOPg), corneal resistance factor (CRF), and corneal compensated intraocular pressure (IOPcc) were obtained. Repeated measurements were conducted on both eyes during a 24-h period, including immediately before and after sleeping. RESULTS: There were no significant differences in any measured variable between right and left eyes [Repeated measurement analysis of variance (Re-ANOVA), p > 0.05]. Diurnal variations (Re-ANOVA, p = 0.001) of CCT, IOPg, IOPcc, and CRF were found during the 24-h period. Significant increases occurred a few minutes after overnight sleep compared with the baseline values at 10:00 PM before sleep (post hoc tests, p = 0.001). However, there were no differences of CH over time during the study period (Re-ANOVA, p = 0.11). A few minutes after awakening, the increase of CCT was not related to the changes of CH, IOPg, IOPcc, or CRF. However, the increase of CRF was significantly correlated with the changes of IOPg. CONCLUSION: Diurnal variation of CH was not detectable in healthy Asian eyes. The diurnal fluctuation of IOP appears not to be associated with CH. However, CRF was increased a few minutes after sleeping, a change that was correlated to the changes of IOPg.

[Submacular fluid after surgery for rhegmatogenous retinal detachment].

OBJECTIVE: To evaluate the accumulation of submacular fluid after surgery for retinal detachment. METHODS: It was a case control study. Sixty seven eyes of sixty six patients with rhegmatogenous retinal detachment which had undergone par plana vitrectomy (PPV) or buckle surgery for retinal detachment were recruited. All patients underwent clinical examination, optical coherence tomography (OCT) scan of the macular at the 1-month postoperative follow-up examination. RESULTS: Submacular fluid after PPV occurred in 21.7% eyes, and was significantly lower than that after buckle surgery(47.7%, chi2 = 4.296, P < 0.05). No significantly differences of submacular fluid rate were found between different surgical technique groups (cryotherapy, transscleral diode photocoagulation, with or without drainage of subretinal fluid) in our buckle surgery series (chi2 = 0.091, 1.588; P > 0.05). There was statistically significant difference in the rate of submacular fluid in cases of buckle surgery series with or without macular detachment (chi2 = 9.537, P < 0.01). Visual acuity improved for 2 lines or more accounted for 80.8% eyes in patients with submacular fluid and for 80.1% eyes in patients without submacular fluid. Comparison of pre- and postoperative LogMAR between these two groups showed no significant difference (F = 0.162, P = 0.688). CONCLUSIONS: The rate of submacular fluid is much lower after PPV than after buckle surgery. Different surgical techniques used in buckle surgery such as cryotherapy or transscleral diode photocoagulation and with or without drainage of subretinal fluid do not influence the rate of postoperative submacular fluid. The rate of submacular fluid is much lower in eyes without macular detachment than in eyes with macular detachment in buckle surgery series.

Central corneal thickness and corneal hysteresis during corneal swelling induced by contact lens wear with eye closure.

PURPOSE: To determine if corneal hysteresis (CH) was associated with increased central corneal thickness (CCT) induced by wearing soft contact lenses during eye closure. DESIGN: A prospective laboratory investigation. METHODS: CCT was measured with a modified optical coherence tomography (OCT), and CH was measured with a Reichert Ocular Response Analyzer (ORA) [Reichert Ophthalmic Instruments, Depew, New York, USA]. The ORA also determined values for intraocular pressure (IOP), corneal compensated IOP (IOPcc), and corneal resistance factor (CRF). One randomly selected eye of 20 non-contact lens wearers (four males and 16 females, age 19.7 +/- 1.1 years) was patched during three hours of soft contact lens wear. Measurements were made before lens insertion, immediately upon removal, and every 20 minutes thereafter for 100 minutes. RESULTS: Immediately after contact lens removal, CCT was increased by 13.1 +/- 2.2% (mean +/- SD) compared with baseline (post hoc, P = .001). After 100 minutes, it remained elevated by 2.4 +/- 1.6% (post hoc, P = .001). However, there were no significant differences of CH at any time after lens wear (analysis of variance [ANOVA], P = .9). Immediately after lens removal, there were significant increases in IOP (post hoc, P = .003) and corneal resistance factor (CRF) (post-hoc, P = .015), but not in IOPcc (post hoc, P = .07). After lens wear, there were significant but weak correlations between the percentage change of CCT (CCT%) and IOP (r = 0.32, P = .001) and IOPcc (r = 0.29, P = .001). However, there was no significant correlation between CCT% and CH (r = 0.07, P = .458). CONCLUSION: CH as measured by ORA was not associated with corneal swelling induced by soft contact lens wear in this study group.