Paired opposite clear corneal incision : time-related changes of its effect and factors on which those changes depend.

PURPOSE To assess astigmatism induced by paired opposite clear corneal incision (OCCI) compared to single incisions and to investigate factors on which its effect depends. METHODS The study comprised 326 eyes from 326 patients. In patients with 1.0 D preoperative corneal astigmatism, a second, opposite clear corneal incision was made (OCCI group, n = 81). Both groups consisted of superior, temporal, and oblique subgroups according to the steepest meridian. Prior to the surgery, and after surgery, repeated keratometry was performed and surgically induced astigmatism (SIA) was calculated using vector analysis. RESULTS Two weeks after the surgery, the SIA was 0.67 ± 0.44 D in the CC group and 1.15 ± 0.65 D in the OCCI group; 9 weeks after the operation, it was 0.61 ± 0.43 D in the CC group and 0.99 ± 0.57 D in the OCCI group (p<0.001). The SIA showed no significant postoperative change in our groups. CONCLUSIONS Opposite clear corneal incision reliably induces about 1.0 D of corneal astigmatism on the steep meridian in proportion to the rate of preoperative astigmatism. Its magnitude is independent of the location of the incisions and its effect remains unchanged during the postoperative period

Examination of ocular biomechanics with a new Scheimpflug technology after corneal refractive surgery

PURPOSE To analyze the early results of a new device measuring ocular biomechanics after corneal refractive surgery. PATIENTS AND METHODS Thirty nine refractive surgery patients were enrolled in the study (age: 32.6±9.9 years). Laser in situ keratomileusis (LASIK) was performed on 52 eyes of 26 patients and photorefractive keratectomy (PRK) was done on 26 eyes of 13 patients. Ten device-specific biomechanical parameters, intraocular pressure (IOP) and pachymetry were measured preoperatively and at day 1, week 1 and month 1 after the surgeries with a new technology based on Scheimpflug imaging (CorVis ST, Oculus). RESULTS In case of LASIK, the day after the procedure, radius values showed significant differences compared to preoperative data. One month after surgery, radius values, velocity of the second applanation and pachymetry showed significant differences compared to preoperative data. In case of PRK, the day after the procedure, significant differences in IOP, maximum amplitude at the apex, A1 time, A2 velocity and highest concavity time were measured. After 1 month of PRK, there were no differences in the parameters compared to preoperative data except pachymetry. CONCLUSIONS We observed that some specific biomechanical parameters changed measured with CorVis ST after LASIK and PRK, in the early postoperative time. However, most of these parameters remain unchanged after one month of LASIK and PRK compared to preoperative data

Intraoperative and postoperative corneal thickness change after collagen crosslinking therapy.

PURPOSE To assess intraoperative and postoperative changes in corneal thickness subsequent to riboflavin-UVA (collagen crosslinking [CXL]) treatment. METHODS Forty-one eyes of 41 patients (mean age 27.97 ± 6.97 years) were treated with CXL technique. During treatment, isotonic riboflavin was instilled and corneal thickness measurements were obtained at the cornea apex, the thinnest point, and the pupil center at 15 and 30 minutes, then 3 days, 1 week, and 1, 3, 6, and 12 months after surgery using Pentacam HR and an ultrasound pachymeter. RESULTS A decrease in corneal thickness was detected 15 minutes intraoperatively with a value of 108.95 ± 48.6 µm, and 112.35 ± 47.3 µm at 30 minutes (p<0.001). Three days after the operation, no deviation was found from the initial values (p = 0.17). No further changes were detected during the follow-up period. CONCLUSIONS Isotonic riboflavin solution used during CXL treatment resulted in a significant decrease in corneal thickness, but its effect had disappeared by postoperative day 3

Accommodation in phakic and pseudophakic eyes measured with subjective and objective methods

PURPOSE To measure accommodation subjectively and objectively and assess anterior segment changes during accommodation in phakic eyes and pseudophakic eyes. SETTING Department of Ophthalmology, Medical Health and Science Centre, University of Debrecen, Debrecen, Hungary. DESIGN Case series. METHODS Subjective and objective accommodation measurements and pupillometry were performed in phakic and pseudophakic patients. Refraction and pupil diameter were recorded with different accommodation stimuli. Corneal higher-order aberrations (HOAs) and anterior chamber depths (ACDs) were detected with a rotating Scheimpflug camera. RESULTS The mean age of the 44 patients in the phakic group was 36.34 years ± 16.6 (SD) and of the 27 patients in the pseudophakic group, 69.3 ± 9.98 years. The mean subjective accommodation was 4.49 ± 3.48 diopters (D) in phakic eyes and showed significant correlation with age, spherical aberration, changes in pupil diameter, and ACD. The mean subjective accommodation was 0.50 ± 0.28 D in pseudophakic eyes. In phakic eyes, the mean objective accommodation was 0.46 ± 1.02 D, 1.06 ± 1.33 D, and 2.2 ± 1.9 D with 2.0 D, 3.0 D, and 5.0 D, respectively, of stimulus. In pseudophakic eyes, measurable objective accommodation was recorded. In phakic eyes, the correlations were significant between these values and age, changes in ACD, pupil size, and corneal spherical aberration. In pseudophakic eyes, the only correlation was with the spherical equivalent value. CONCLUSIONS The magnitude of accommodation was greater with subjective measures than objective measures. In pseudophakic eyes, senile miosis and HOAs can be regarded as underlying factors in subjective accommodation; however, objective accommodation is not clinically significant. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned

Scheimpflug imaged corneal changes on anterior and posterior surfaces after collagen cross-linking

<b>AIM:</b> To compare the anterior and posterior corneal parameters before and after collagen cross-linking therapy for keratoconus.<b>METHODS:</b> Collagen cross-linking was performed in 31 eyes of 31 keratoconus patients (mean age 30.6±8.9y). Prior to treatment and an average 7mo after therapy, Scheimpflug analysis was performed using Pentacam HR. In addition to corneal thickness assessments, corneal radius, elevation, and aberrometric measurements were performed both on anterior and posterior corneal surfaces. Data obtained before and after surgery were statistically analyzed.<b>RESULTS:</b> In terms of horizontal and vertical corneal radius, and central corneal thickness no deviations were observed an average 7mo after operation. Corneal higher order aberration showed no difference neither on anterior nor on posterior corneal surfaces. During follow-up period, no significant deviation was detected regarding elevation values obtained by measurement in mm units between the 3.0-8.0 mm-zones.<b>CONCLUSION:</b> Corneal stabilization could be observed in terms of anterior and posterior corneal surfaces, elevation and higher order aberration values 7mo after collagen cross-linking therapy for keratoconus

Assessment of endothelial cell density and corneal thickness in corneal grafts an average of 5 years after penetrating keratoplasty

BACKGROUND Corneal transparency is a useful indicator for corneal function. Our aim was to investigate central corneal endothelial cells and corneal thickness in transplanted corneas at an average of 5.4 years after penetrating keratoplasty PATIENTS AND METHODS The study involved 68 perforated keratoplasty patients with at least a 1 year follow-up. Post-operatively, the central corneal endothelial layer was observed using a contact specular microscope. Central endothelial cell density, corneal thickness and the coefficient of variation of endothelial size were statistically analysed. RESULTS The post-operative follow-up time was ranging from 12 months to 23 years. Endothelial cell density (ECD) was 1,501 ± 249 cell/mm(2). The average cell size was 673.6 ± 98.3 μm(2), and the coefficient of variation of cell size was 0.61 ± 0.11. No difference in ECD was detected between diagnostic groups. Corneal thickness was 0.56 ± 0.06 mm. Correlation between ECD and post-operative time was not significant (r = 0.02; p = 0.85). CONCLUSION Our study concluded that ECD showed a higher rate of decrease after penetrating keratoplasty with no relation to pre-operative diagnosis

A survey of corneal changes caused by daily wear silicone hydrogel contact lenses

Purpose: The examination of the effects of second generation lotrafilcon B silicone hydrogel (SiH) lenses on the cornea when worn for three years of daily wear. Material and Methods: 55 healthy patients were divided into two groups: current hydrogel contact lens wearers refitted with lotrafilcon B lenses (Group 1; 28 patients) and neophyte contact lens wearers (Group 2; 27 patients). Each patient's subjective eye comfort was measured with a self-administered questionnaire. The corneas were analyzed using contact specular microscope to measure corneal thickness and the endothelium before the SiH lenses were fitted after four weeks, one month, six months, one year, two years, and three years of lens wear. Results: Subjective complaints of patients in Group 1 were reduced; however patients in Group 2 experienced discomfort during the first two to four weeks of use. In Group 1, objective examinations identified a decrease in endothelial cell density. In Group 2, the endothelial cell density increased slightly in the first two years but decreased after three years. The results indicate that lotrafilcon B slows down the deleterious effects of contact lenses. The coefficient of variation significantly decreased after six months in Group 1 (0.47 vs 0.44; p = 0.049), whereas, in Group 2, the hexagonal cells improved significantly after one month (27.78 vs 28.25; p = 0.025). Conclusion: Based on the subjects involved and the period of time under examination, it can be concluded that high-Dk SiH lenses support the physiological metabolism and functions of the cornea by improving oxygen provision

A clinical feasibility study to evaluate the safety and efficacy of PEOT/PBT implants for human donor site filling during mosaicplasty

Mosaicplasty has become a well-accepted treatment modality for articular cartilage lesions in the knee. Postoperative bleeding remains potentially concerning. This study evaluates the porous poly(ethylene oxide)terephthalate/poly(butylene terephthalate) (PEOT/PBT) implants used for donor site filling. Empty donor sites were the controls. After 9 months, MRI, macroscopical and histological analysis were carried out. Treated defects did not cause postoperative bleeding. No adverse events or inflammatory response was observed. PEOT/PBT implants were well integrated. Empty controls occasionally showed protrusion of repair tissue at the defect margins. Surface stiffness was minimally improved compared to controls. Existing polymer fragments indicated considerable biodegradation. Histological evaluation of the filled donor sites revealed congruent fibrocartilaginous surface repair with proteoglycan-rich domains and subchondral cancellous bone formation with interspersed fibrous tissue in all implanted sites. The PEOT/PBT implants successfully reduce donor site morbidity and postoperative bleeding after mosaicplasty