Influence of corneal biomechanical properties on surgically induced astigmatism in cataract surgery.

PURPOSE: To perform an overall follow-up of the morphologic, optical, and biomechanical properties of the cornea to determine new parameters influencing the refractive outcomes of cataract surgery. DESIGN: Clinical study. METHODS: Patients scheduled for cataract surgery were assessed for surgically induced corneal astigmatism (SIA) and higher-order aberrations, (HOAs) using a Scheimpflug rotating camera (Pentacam) together with corneal imaging by optical coherence tomography (Spectralis) and biomechanical analysis by the Ocular Response Analyzer preoperatively and 1, 7, and 30 days postoperatively. The central and peripheral corneal thicknesses; incision width, length, and architecture; corneal hysteresis (CH); and corneal resistance factor (CRF) were computed to identify new parameters influencing corneal optical changes that determine the final refractive result. RESULTS: The study enrolled 40 patients (40 eyes). The SIA and HOAs were significantly lower after microincision surgery (≤ 2.2 mm) than after small-incision surgery (2.75 mm) (both P<.01). The CRF was significantly reduced with a direct corneal incision compared with a constructed incision (P<.01). Multivariate analysis showed that SIA was correlated not only with incision width (P<.05) but also with preoperative CH (P<.01). Corneal 3rd-order trefoil depended on incision width (P<.01). CONCLUSIONS: In addition to the well-known influence of incision size on SIA, CH also modulates optical changes. The biomechanical features of the cornea should be taken into account preoperatively to better predict the refractive outcomes of cataract surgery.

Tear film osmolarity in patients treated for glaucoma or ocular hypertension.

PURPOSE: To evaluate tear film osmolarity in patients treated with intraocular pressure-lowering medications. METHODS: Forty patients treated for glaucoma or ocular hypertension (OHT) were consecutively recruited for the study. Each patient was asked to complete an evaluation of ocular surface disease symptoms, the Ocular Surface Disease Index, and underwent a complete evaluation of the ocular surface including measurement of tear film osmolarity, Schirmer test, tear breakup time (TBUT), and corneal and conjunctival staining. RESULTS: Twenty-four patients (60%) reported ocular surface disease symptoms. Nineteen patients (47.5%) had a tear osmolarity ≤308 mOsms/L, 11 (27.5%) between 309 and 328 mOsms/L, and 10 (25%) >328 mOsms/L. A tear deficiency was observed in 20 patients (50%). Twenty-seven patients (67.5%) had an abnormal tear quality analyzed with TBUT, and 16 patients (40%) showed positive staining using the Oxford schema. Tear osmolarity was significantly correlated to Ocular Surface Disease Index (r = 0.486; P = 0.002) and TBUT (r = -0.49; P = 0.009). There was a statistically significant correlation between tear osmolarity and the number of drugs (r = 0.409; P = 0.009), the number of instillations (r = 0.405; P = 0.01), and the number of instillations of preserved eye drops (r = 0.629; P < 0.0001). Using the multiple regression method, tear osmolarity remained significantly correlated to the number of instillations of preserved eye drops (P = 0.004). CONCLUSION: Tear osmolarity was increased in patients treated for glaucoma or OHT, particularly in those using multiple preserved eye drops. The evaluation of the ocular surface of patients treated for glaucoma or OHT may benefit from such analysis, and future trials for new intraocular pressure-lowering eye drops should thus evaluate tear osmolarity.

The relationship between subbasal nerve morphology and corneal sensation in ocular surface disease.

PURPOSE: The purpose of this study was to evaluate the relationship between the in vivo confocal microscopic (IVCM) morphology of subbasal corneal nerves and corneal sensitivity in patients with ocular surface disease. METHODS: Ten healthy volunteers (control group), 12 patients with dry eye (dry-eye group), and 14 patients treated with IOP-lowering topical medications (glaucoma group) were included. Central corneal sensation was measured using the contact Cochet-Bonnet esthesiometer. IVCM of the cornea was performed and the following subbasal corneal nerves parameters were analyzed: density, number, width, number of beadings, number of branching, tortuosity, and reflectivity. One eye of each subject was included in the study. RESULTS: Corneal sensitivity was significantly decreased in dry-eye and glaucoma patients compared with controls. The density and number of subbasal corneal nerves were also significantly decreased in dry eye and glaucoma patients compared with controls. There was no difference in terms of subbasal nerve width, number of beadings, tortuosity, reflectivity, and number of branching between the dry-eye, the glaucoma, and the control groups. In all subjects, corneal sensitivity correlated positively with the density and number of subbasal nerves; however, in the dry-eye group, corneal sensitivity correlated with the density and the number of nerves, whereas in the glaucoma group, corneal sensitivity correlated only with the tortuosity of subbasal nerves. CONCLUSIONS: The relationship between corneal sensation and subbasal nerve morphology, as evaluated with IVCM, depends on the pathophysiological mechanism of ocular surface disease.

Spontaneous thrombosis of an orbital arteriovenous malformation revealing hereditary haemorrhagic telangiectasia (Rendu-Osler-Weber disease). A case report.

Hereditary Haemorrhagic Telangiectasia (HHT) is a genetic disorder responsible for cutaneous or mucosal telangiectasia and arteriovenous malformations (AVMs). The most frequent locations are lung and brain. In contrast, orbital AVMs are very rare. We describe a case of symptomatic orbital arteriovenous malformation due to spontaneous thrombosis. A 65-year-old woman was referred for chronic right eye proptosis associated with dilation of conjunctival vessels with a jellyfish pattern. Right visual acuity was 20/40 and intraocular pressure was 40 mmHg. Personal and familial history of recurrent epistaxis, associated with multiple telangiectasia within lips and palate, led to the diagnosis of HHT. Magnetic resonance imaging (MRI) completed with cerebral angiography found a giant and occluded AVM within the right orbit. Other AVMs were also found in brain and chest, confirming the diagnosis. Antiglaucomatous eyedrops were added to reduce intraocular pressure and a steroid therapy was begun. Two months later, visual acuity decreased in the right eye, due to a central retinal vein thrombosis. In conclusion, Most brain or pulmonary AVM can be treated by embolization. By contrast, this treatment in case of orbital location can lead to central retinal artery and/or central retinal vein occlusion, which may also appear as a spontaneous complication of the orbital AVM. Therapeutic management of orbital AVM is thus not standardized, and the balance between spontaneous and iatrogenic risk of visual loss has to be taken into account.