ABSTRACT
OBJECTIVE: In this report, we investigated the association between the intraocular pressure (IOP) values by two different measurement methods and the corneal biomechanical properties in a patient with keratoconus and secondary glaucoma due to pseudoexfoliation syndrome who developed a marked elevation of intraocular pressure in the right eye. METHODS: IOP was measured over a period of 3 days with Goldmann applanation tonometry (GAT) and dynamic contour tonometry (Pascal tonometry, DCT). Corneal hysteresis (CH) and corneal resistance factor (CRF) were estimated with the aid of an ocular response analyzer (ORA). RESULTS: CH and CRF were significantly reduced in the right eye compared to the left eye throughout the period of observation (paired t-test, p < 0.001). The difference between both methods of IOP measurement in the right eye was statistically significant for IOP < 30 mmHg by GAT (Wilcoxon test, p = 0.004). For IOP values > 30 mmHg by GAT, there was no statistically significant difference between DCT and GAT (Wilcoxon test, p = 0.0625). CONCLUSIONS: This observation supports the clinical hypothesis that a significant decrease in CH translates to a decreased correlation of CH and IOP recordings by GAT and, furthermore, suggests that after a critical point of CH reduction, the impact of CH on GAT may be comparable to that on DCT.
Subject(s)
Exfoliation Syndrome , Glaucoma , Keratoconus , Cornea , Humans , Intraocular Pressure , Tonometry, OcularABSTRACT
Intracorneal ring segment (ICRS) implantation represents a modern, minimally invasive, surgical option for visual improvement in patients with keratoconus. ICRS modify the corneal geometry in a manner that enhances its refractive properties and thereby, they improve visual acuity. It is well-documented that implantation of ICRS decreases the keratometric readings, spherical equivalent and cylinder, reduces high-order aberrations and improves uncorrected distance visual acuity (UDVA) and best-corrected distance visual acuity (BCDVA) in patients with keratoconus. Success rate after ICRS implantation is high, depending on appropriate patient selection and adherence to suitable implantation nomograms, and most important, the overall complication rate is very low. This review is summarizing current indications/contra-indications for ICRS implantation, implantation techniques, clinical outcomes and potential complications, shedding light on myths and realities related to this innovative surgical option.
ABSTRACT
Keratoconus is a relatively common ectatic, non-inflammatory corneal disorder that involves gradual visual deterioration through progressive alteration of the shape of the cornea. The corneal thinning, irregular astigmatism and higher order aberrations that occur as the disease progresses pose major challenges in the visual rehabilitation of such patients. This paper summarizes the current literature regarding the results of visual enhancement procedures in patients with stable keratoconus treated with standalone anterior or posterior chamber phakic intraocular lens implantation and monofocal, toric or multifocal toric intraocular lens implantation following phacoemulsification for age-related cataract extraction or refractive lens exchange.
