To evaluate the corneal volume, pachymetry, and correlation of anterior and posterior corneal shape in subclinical and clinical keratoconus. Vissum Corporation, Alicante, Spain. Eyes were placed into 1 of 4 groups as follows: keratoconus 2 (grade II), keratoconus 1 (grade I), subclinical (subclinical keratoconus), and control (normal eyes). All eyes had an ophthalmologic examination including corneal evaluation (curvature, elevation, asphericity, pachymetry, corneal volume) by rotating Scheimpflug imaging (Pentacam). The posterior-anterior corneal power ratio was also calculated. Seventy-one eyes (51 patients; aged 16 to 64 years) were evaluated. Astigmatism and keratometry of both corneal surfaces were statistically significantly higher in the keratoconus 1 and 2 groups (Por=-0.81) was found between anterior and posterior curvature in the normal and subclinical groups; the correlation was weaker in clinical keratoconus cases (ror=0.81). The posterior-anterior corneal power ratio was significantly higher in the keratoconus 2 group than in the other groups (P<or=.01). Pachymetric readings were progressively lower in eyes with subclinical, early, or moderate keratoconus (P<.01). The corneal volume was statistically significantly lower in the keratoconus 2 group than in the other groups (P = .04). The correlation between anterior and posterior corneal curvature was lower in keratoconus, although the correlation between anterior and posterior astigmatism was maintained.

The increasing volume of patients interested in refractive surgery and the new treatment options available for keratoconus have generated a higher interest in achieving a better characterization of this pathology. The ophthalmic devices for corneal analysis and diagnosis have experienced a rapid development during the past decade with the implementation of technologies such as the Placido-disk corneal topography and the introduction of others such as scanning-slit topography, Scheimpflug photography, and optical coherence tomography, which are able to accurately describe not only the geometry of the anterior corneal surface but also that of the posterior surface, as well as pachymetry and corneal volume. Specifically, anterior and posterior corneal elevation, corneal power, pachymetry maps, and corneal coma-like aberrometry data provide sufficient information for an accurate characterization of the cornea to avoid misleading diagnoses of patients and provide appropriate counseling of refractive surgery candidates. No author has a financial or proprietary interest in any material or method mentioned.

The gold standard treatments in amblyopia are penalizing therapies, such as patching or blurring vision with atropine that are aimed at forcing the use of the amblyopic eye. However, in the last years, new therapies are being developed and validated, such as dichoptic visual training, aimed at stimulating the amblyopic eye and eliminating the interocular supression. To evaluate the effect of dichoptic visual training using a virtual reality head mounted display in a sample of anisometropic amblyopic adults and to evaluate the potential usefulness of this option of treatment. A total of 17 subjects (10 men, 7 women) with a mean age of 31.2 years (range, 17–69 year) and anisometropic amblyopia were enrolled. Best corrected visual acuity (BCVA) and stereoacuity (Stereo Randot graded circle test) changes were evaluated after 8 sessions (40 min per session) of dichoptic training with the computer game Diplopia Game (Vivid Vision) run in the Oculus Rift OC DK2 virtual reality head mounted display (Oculus VR). Mean BCVA in amblyopic eye improved significantly from a logMAR value of 0.58 ± 0.35 before training to a post-training value of 0.43 ± 0.38 (p < 0.01). Forty-seven percent of the participants achieved BCVA of 20/40 or better after the training as compared to 30% before the training. Mean stereoacuity changed from a value of 263.3 ± 135.1 before dichoptic training to a value of 176.7 ± 152.4 s of arc after training (p < 0.01). A total of 8 patients (47.1%) before dichoptic treatment had unmeasurable stereoacuity while this only occurred in 2 patients (11.8%) after training. Dichoptic training using a virtual reality head mounted display seems to be an effective option of treatment in adults with anisometropic amblyopia. Future clinical trials are needed to confirm this preliminary evidence. Trial ID: ISRCTN62086471 . Date registered: 13/06/2017. Retrospectively registered

PURPOSE: To evaluate and compare the visual, refractive, contrast sensitivity, and aberrometric outcomes with a diffractive bifocal and trifocal intraocular lens (IOL) of the same material and haptic design. METHODS: Sixty eyes of 30 patients undergoing bilateral cataract surgery were enrolled and randomly assigned to one of two groups: the bifocal group, including 30 eyes implanted with the bifocal diffractive IOL AT LISA 801 (Carl Zeiss Meditec, Jena, Germany), and the trifocal group, including eyes implanted with the trifocal diffractive IOL AT LISA tri 839 MP (Carl Zeiss Meditec). Analysis of visual and refractive outcomes, contrast sensitivity, ocular aberrations (OPD-Scan III; Nidek, Inc., Gagamori, Japan), and defocus curve were performed during a 3-month follow-up period. RESULTS: No statistically significant differences between groups were found in 3-month postoperative uncorrected and corrected distance visual acuity ( P ⩾ .21). However, uncorrected, corrected, and distance-corrected near and intermediate visual acuities were significantly better in the trifocal group ( P < .01). No significant differences between groups were found in postoperative spherical equivalent ( P = .22). In the binocular defocus curve, the visual acuity was significantly better for defocus of −0.50 to −1.50 diopters in the trifocal group ( P ⩽ .04) and −3.50 to −4.00 diopters in the bifocal group ( P ⩽ .03). No statistically significant differences were found between groups in most of the postoperative corneal, internal, and ocular aberrations ( P ⩾ .31), and in contrast sensitivity for most frequencies analyzed ( P ⩾ .15). CONCLUSIONS: Trifocal diffractive IOLs provide significantly better intermediate vision over bifocal IOLs, with equivalent postoperative levels of visual and ocular optical quality. [ J Refract Surg. 2014;30(10):666–672.]

Laser refractive surgery has increased markedly in recent years, making the detection of corneal abnormalities extremely relevant. For this reason, an accurate diagnosis of clinical or subclinical keratoconus is critical. Corneal topography is the primary diagnostic tool for keratoconus detection, and pachymetry data and corneal aberrations are also commonly used. Recently, tomographic measurements using optical coherence tomography and corneal biomechanical indices have been used. In incipient and subclinical keratoconus, the use of a single parameter as a diagnostic factor is not sufficiently accurate. In these cases, the use of algorithms and predictive models is necessary. In addition, determining whether the disease will progress is crucial to selecting the most appropriate treatment. Some factors, such as age, keratometric indices, corneal elevation data, and corneal thickness, seem to be useful in predicting keratoconus progression.