Rita Mencucci

Effects of riboflavin/UVA corneal cross-linking on keratocytes and collagen fibres in human cornea

Purpose:  To evaluate the effects of corneal cross‐linking on keratocytes and collagen fibres in human corneas.

Corneal endothelial damage after cataract surgery : Microincision versus standard technique

PURPOSE: To compare corneal endothelial changes after phacoemulsification performed with a standard technique versus a bimanual microincision cataract surgery (MICS) technique. SETTING: University ophthalmology department. METHODS: Eighty patients scheduled for routine cataract surgery were randomized into 2 groups; 40 eyes had standard stop‐and‐chop phacoemulsification (standard group) and 40 eyes had stop‐and‐chop phacoemulsification with microincision surgery (MICS group). Central corneal endothelial cell counts, coefficient of variation in cell size, hexagonality, and pachymetry were assessed preoperatively and 1 and 3 months postoperatively. RESULTS: The mean preoperative cell count in the entire sample was 2245 cells/mm2 ± 37 (SE). The mean decreased by 102 cells at 1 month (95% confidence interval [CI], −133 to −71; P<.001) and by 144 cells at 3 months (95% CI, −187 to −102; P<.001). The difference between the standard group and the MICS group was 25 cells at baseline (95% CI, −169 to 120 cells; P = .739), 19 cells at 1 month (95% CI, −163 to 126; P = .799), and 19 cells at 3 months (95% CI, −164 to 125; P = .793). There were no changes in the coefficient of variation or morphology in the overall sample, and the pattern of change did not differ between the 2 groups. Corneal thickness increased by 10.2 μm in the overall sample (95% CI, +4.5 to +16.0; P<.001) and approached baseline values by 3 months with an increase of 3.4 μm (95% CI, −4.1 to 10.8; P = .372). There was no difference in corneal thickness between the groups. CONCLUSION: No significant differences in corneal endothelial cell loss or endothelial morphology were found between MICS and standard incision techniques.

Transepithelial corneal collagen cross-linking in ultrathin keratoconic corneas.

Background The purpose of this paper was to report the results of transepithelial corneal collagen cross-linking (CXL) with modified riboflavin and ultraviolet A irradiation in patients affected by keratoconus, each with thinnest pachymetry values of less than 400 μm (with epithelium) and not treatable using standard de-epithelialization techniques. Methods Sixteen patients affected by progressive keratoconus with thinnest pachymetry values ranging from 331 μm to 389 μm underwent transepithelial CXL in one eye using a riboflavin 0.1% solution in 15% Dextran T500 containing ethylenediamine tetra-acetic acid 0.01% and trometamol to enhance epithelial penetration. The patients underwent complete ophthalmological examination, including endothelial cell density measurements and computerized videokeratography, before CXL and at one day, one week, and one, 6, and 12 months thereafter. Results Epithelial healing was complete in all patients after one day of use of a soft bandage contact lens. No side effects or damage to the limbal region was observed during the follow-up period. All patients showed slightly improved uncorrected and spectacle-corrected visual acuity; keratometric astigmatism showed reductions (up to 5.3 D) and apical ectasia power decreased (Kmax values reduced up to 4.3 D). Endothelial cell density was unchanged. Conclusion Application of transepithelial CXL using riboflavin with substances added to enhance epithelial permeability was safe, seemed to be moderately effective in keratoconic eyes with ultrathin corneas, and applications of the procedure could be extended to patients with advanced keratoconus.

Ophthalmological aspects in allogenic bone marrow transplantation : Sjögren-like syndrome in graft-versus-host disease

Purpose. A major complication of allogenic bone marrow transplantation (BMT) is graft-versus-host disease (GVHD), characterized principally by involvement of the eyes, producing a Sjögren-like syndrome (SLS). This study assessed the predictive role of the eye involvement in the onset of GVHD. Methods. Thirty-five patients transplanted for hematological malignancies were routinely examined for ocular manifestation of dry eye. Examination includes the Schirmer I test, break-up time, Lissamine Green staining, fluorescein test, lactoferrin test and impression cytology. A threshold was established for quantitative analysis of SLS. Results. Fifteen of 35 patients (40%) developed SLS during long-term follow-up. Ten of these (77%) developed acute or chronic GVHD. Conclusions. The possible etiology of SLS includes three factors: total body irradiation, ocular toxicity of chemotherapy and GHVD. A correlation was found between poor-prognosis GVHD and the occurrence of SLS.

Endophthalmitis prophylaxis in cataract surgery: overview of current practice patterns in 9 European countries.

Data on practice patterns for prophylaxis against infectious postoperative endophthalmitis (IPOE) during cataract surgery in 9 European countries were searched in national registers and reviews of published surveys. Summary reports assessed each nations IPOE rates, nonantibiotic prophylactic routines, topical and intracameral antibiotic use, and coherence to the European Society of Cataract & Refractive Surgeons (ESCRS) 2007 guidelines. Although the reliability and completeness of available data vary between countries, the results show that IPOE rates differ significantly. Asepsis routines with povidone-iodine and postoperative topical antibiotics are generally adopted. Use of preoperative and perioperative topical antibiotics as well as intracameral cefuroxime varies widely between and within countries. Five years after publication of the ESCRS guidelines, there is no consensus on intracameral cefuroxime use. Major obstacles include legal barriers or persisting controversy about the scientific rationale for systematic intracameral cefuroxime use in some countries and, until recently, lack of a commercially available preparation.

Experimental study on the healing process following laser welding of the cornea

An experimental study evaluating the application of laser welding of the cornea and the subsequent healing process is presented. The welding of corneal wounds is achieved after staining the cut walls with a solution of the chromophore indocyanine green, and irradiating them with a diode laser (810 nm) operating at low power (60 to 90 mW). The result is a localized heating of the cut, inducing controlled welding of the stromal collagen. In order to optimize this technique and to study the healing process, experimental tests, simulating cataract surgery and penetrating keratoplasty, were performed on rabbits: conventional and laser-induced suturing of corneal wounds were thus compared. A follow-up study 7 to 90 days after surgery was carried out by means of objective and histological examinations, in order to optimize the welding technique and to investigate the subsequent healing process. The analyses of the laser-welded corneas evidenced a faster and more effective restoration of the architecture of the stroma. No thermal damage of the welded stroma was detected, nor were there foreign body reactions or other inflammatory processes.

Riboflavin and ultraviolet A collagen crosslinking: In vivo thermographic analysis of the corneal surface

PURPOSE: To assess the possible thermal damage to the cornea during combined riboflavin and ultraviolet‐A crosslinking using in vivo surface thermographic analysis. SETTING: Department of Oto‐Neuro‐Ophthalmological Surgical Sciences, Eye Clinic, University of Florence, Florence, Italy. METHODS: Collagen crosslinking was performed on a day‐surgery basis under aseptic conditions with traditional techniques. During the procedure, temperature measurements on the corneal surface were taken using an infrared thermocamera. The temperature values were detected in the area directly exposed to light irradiation, selecting it in the acquired thermographic image. Because the aim of the study was to consider the thermal damage that may be induced during the procedure, the maximum temperature value detected in the area studied was recorded and considered for successive analysis. RESULTS: Infrared thermocamera measurements of the corneal surface during crosslinking treatment showed that the temperature was constant during the entire procedure and remains under the threshold of thermal injury to corneal collagen. CONCLUSION: Corneal collagen crosslinking was a safe procedure that did not cause thermal injury to the corneal surface.

Ultrasound thermal damage to rabbit corneas after simulated phacoemulsification

PURPOSE: To determine rabbit cornea thermal tolerance and evaluate the effects of ultrasound (US) on this tissue after applying defined US heat doses. SETTING: Eye Clinic; Anatomy Histology and Forensic Medicine, University of Florence, Florence, Italy. METHODS: Hyperthermia was induced in rabbit corneas using US, simulating a phacoemulsification procedure. The US power was set at 100% in continuous mode, and temperature values were reached within 10 seconds of the onset of US treatment. Corneal surface temperatures were continuously monitored and recorded by thermographic registration. The eyes of 16 rabbits were examined: 4 controls, 8 treated at 40°C for 10 seconds, 8 treated at 50°C for 10 seconds, and 12 treated at 60°C for 10 seconds. All 32 corneal buttons were removed and prepared for light microscopic evaluation with hematoxylin and eosin staining, trichromic staining, and zinc iodide–osmium tetroxide solution. The 12 corneas treated at 60°C for 10 seconds were also processed for immunohistochemical analysis. RESULTS: Corneas at 40°C for 10 seconds were grossly and histologically normal and were not different from control corneas. Corneas at 50°C for 10 seconds showed initial stromal damage with collagen disorganization, mild stromal edema, and initial signs of keratocyte damage. Half of the corneas at 60°C for 10 seconds were examined at time 0 and the other half after 1 week. At time 0, massive corneal damage with epithelial cell edema, collagen disorganization, severe stromal edema, intrastromal vacuole formation, plump keratocyte nuclei, and endothelial cell detachment were found, as was a severely impaired nerve plexus. At 1‐week follow‐up, corneas showed persistent stromal and endothelial cell edema with an increase activated keratocytes and mitotic features in the stroma and the epithelial layer. CONCLUSIONS: Rabbit corneas showed a considerable tolerance to US damage up to 50°C. Higher thermal doses produced severe histological damage, even though corneas showed a considerable plasticity due to their regenerative capacity.

Thermography used for analysis and comparison of different cataract surgery procedures based on phacoemulsification.

Thermography has been employed to analyze and compare three cataract surgery procedures performed in vivo with phacoemulsification, namely, the Sovereign phacoemulsification system with a traditional technique, the Sovereign WhiteStar phacoemulsification system with a traditional technique and the Sovereign WhiteStar phacoemulsification system with a bimanual technique. During the entire surgical procedure, the temperature of the ocular surface was monitored. The temperature values in the area where the phaco probe was inserted in the eye were measured, and the quantities of heat transmitted to the eye in the different procedures were assessed through suitable indices. In this study the highest temperature measured for each procedure during the surgical operation was 44.9 degrees C for the Sovereign phacoemulsification system with a traditional technique, 41 degrees C for the Sovereign WhiteStar phacoemulsification system with a traditional technique and 39.5 degrees C for the Sovereign WhiteStar phacoemulsification system with a bimanual technique, which is also the surgical procedure having the lowest thermal impact on the eye, i.e., the one in which the temperature peaks are lowest in amplitude and the least amount of heat is transmitted to the eye. Thermography, used in this study as a temperature monitoring instrument, has allowed analysis to be effected through a useful and advantageous methodology, totally non-invasive as regards both surgeon and patient, and has been applied in vivo without requiring any change in the surgical procedure.

Astigmatism correction with toric intraocular lenses: wavefront aberrometry and quality of life

Background/aim To evaluate wavefront aberrations and subjective quality of life after toric intraocular lens (TIOL) implantation. Methods Three groups of subjects who underwent unilateral cataract surgery with intraocular lens (IOL) implantation were compared: (1) toric group (n=40): corneal astigmatism >1.50 D, implanted with Acrysof toric SN60TT IOL (Alcon Inc, Fort Worth, Texas, USA); (2) astigmatic SN60AT group (n=40): corneal astigmatism >1.50 D, implanted with Acrysof SN60AT IOL; and (3) control group (n=40): corneal astigmatism <1.00 D, implanted with Acrysof SN60AT IOL. Uncorrected distance visual acuity (UDVA), refraction, lower order astigmatism (Z22, Z−22), Strehl ratio and the modulation transfer function area ratio were evaluated over a 3 month follow-up period. A standardised quality of life test (National Eye Institute Refractive Error Quality of Life Instrument-42) was distributed to both astigmatic groups 3 months postoperatively. Results Postoperative UDVA and aberrometric values were significantly better (p<0.001) and mean postoperative spherical equivalent was significantly lower (p<0.05) in the toric and control groups compared with the astigmatic SN60AT group. The toric group had significantly better postoperative quality of life compared with the astigmatic SN60AT group (p<0.05). Conclusions Acrysof TIOL implantation resulted in better visual, refractive and aberrometric results than SN60AT spherical IOL implantation in astigmatic patients, similar to the control group. The better objective optical and retinal image quality resulted in better subjective quality of life after TIOL implantation.