Biomedical subjects

Mohamed H Shabayek

Publications and source records attributed to Mohamed H Shabayek.

5 recordsLinked to original sources

PubMed2006

Analysis of results related to good and bad outcomes of Intacs implantation for keratoconus correction.

PURPOSE: To evaluate factors influencing good and poor outcomes after intracorneal ring segment implantation to correct keratoconus. SETTING: Instituto Oftalmológico de Alicante (Vissum Corporation), University of Miguel Hernandez, Alicante, Spain. METHODS: A retrospective comparative study of the visual outcome, 25 eyes of 21 patients were implanted after intracorneal ring segments (Intacs, Addition Technology) as a method to correct keratoconus. Outcomes were evaluated 6 months after implantation based on the visual results. Group A comprised 20 eyes that gained 3 lines or more of best spectacle-corrected visual acuity (BSCVA) to correct keratoconus, and Group B comprised 5 eyes that lost 1 line of BSCVA. RESULTS: In Group A, the preoperative mean BSCVA was 0.43 (20/50) and the postoperative mean BSCVA, 0.82 (20/20) (P< or =.0001). In Group B, the preoperative mean BSCVA was 0.36 (20/63) and the postoperative mean BSCVA, 0.24 (20/80) (P< or =.02). The preoperative mean sphere power was 3.90 diopters (D) greater in Group B than in Group A (P< or =.007); the mean spherical equivalent was 4.36 D greater (P< or =.007), and the mean K-reading was 6.91 D greater (P< or =.001). The postoperative reduction in spherical dioptric power was 2.11 D (P< or =.027) and the mean spherical equivalent, 2.81 D (P< or =.003), significant only in Group A. The reduction in mean central K-readings was 4.30 D (P< or =.0001) in Group A and 6.19 D (P< or =.014) in Group B. The correlation of the preoperative mean K value to the postoperative BSCVA was significant at the .01 level by the Pearson test (-0.67). In Group A, all eyes (100%) had a mean K-reading < or =53 D. In Group B, 4 eyes (80%) had a mean K-reading > or =55 D. CONCLUSION: Intacs provided better results in visual acuity and corneal topography quality and significantly reduced the spherical equivalent in eyes with keratoconus with relatively low mean K values (< or =53 D) and a relatively low spherical equivalent. In advanced keratoconus (mean K-reading > or =55 D), poor results can be anticipated.

Adult↗

PubMed2006

Intracorneal ring segments for keratoconus correction: long-term follow-up.

PURPOSE: To evaluate long-term results and stability of intracorneal ring segment (Intacs) implantation for keratoconus correction. SETTING: Vissum, Instituto Oftalmológico de Alicante and University of Miguel Hernandez, Alicante, Spain. METHODS: This retrospective study comprised 13 eyes operated on between April 2000 and December 2001 that had Intacs implantation for keratoconus correction. The outcomes were evaluated at 6, 12, 24, and 36 months in all eyes and at 48 months (6 eyes). RESULTS: Mean best spectacle-corrected visual acuity (BSCVA) increased from 0.46 (20/50) preoperatively to 0.66 (20/30) postoperatively (P< or =.001). Mean decrease of inferior-superior (I-S) asymmetry was 2.81 diopters (D) (P< or =.02), and the average K-value was 3.13 D (P< or =.001). Mean difference between 6 and 36 months (stability) showed no significant difference regarding BSCVA (P< or =.5) and I-S asymmetry (P< or =.6). Although a significant increase was noticed in the average K by 1.67 D (P< or =.002), at 36 months it did not reach the initial preoperative values. CONCLUSION: Intacs increased the BSCVA and decreased I-S asymmetry with stability up to 36 months. In spite of the decrease of the K-values at 6 months, a further significant increase was detected 36 months after surgery.

Adult↗

PubMed2006

Hyperopic LASIK following intracorneal hydrogel lens explantation.

PURPOSE: To report hyperopic LASIK results after intracorneal hydrogel lens explantation in a bilateral hyperopic patient. METHODS: Slit-lamp examination showed diffuse corneal opacity around the lens edge and over the anterior lens surface affecting both eyes with uncorrected visual acuity of 0.4 in the right eye and 0.5 in the left eye. RESULTS: The intracorneal hydrogel lenses were explanted, and 6 months later hyperopic LASIK using the Schwind ESIRIS excimer laser (Schwind, Kleinostheim, Germany) was performed after lifting the same flap for the intracorneal hydrogel lens implantation. Six months after hyperopic LASIK, visual acuity recovered to the initial preoperative best spectacle-corrected levels: right eye 0.8 with +1.50 D sphere and left eye 0.9 with +1.00 -0.50 x 90 degrees. Central corneal transparency also fully recovered. CONCLUSIONS: Hyperopic LASIK is a possible alternative after intracorneal hydrogel lens explantation in hyperopic eyes.

Anterior Eye Segment↗

PubMed2006

Intracorneal asymmetrical rings for keratoconus: where should the thicker segment be implanted?

PURPOSE: To report a 20-year-old man who presented with monocular diplopia in the right eye with uncorrected visual acuity (UCVA) of 0.3 and best spectacle-corrected visual acuity (BSCVA) of 1.0 with -0.50 -3.00 x 45 degrees. METHODS: Clinical examination and corneal topography revealed grade I keratoconus in the right eye. Intracorneal ring segments (INTACS; Addition Technology, Des Plaines, III) were implanted in May 2004 without surgical complications at 415 microm (70% of the corneal thickness), with the 450-microm segment implanted superiorly and the 250-microm segment inferiorly. RESULTS: For 2 months postoperatively, BSCVA remained at 0.4 with +1.50 -4.50 x 25 degrees. The segments were reversed, implanting the 450-microm (thick) segment inferiorly and the 250-microm (thin) segment superiorly. One week later, UCVA was 1.0 and remained stable for 3 months after reimplantation. CONCLUSIONS: This report shows that implanting the thicker segment inferiorly provides better visual results.

Adult↗

PubMed2006

Corneal higher order aberrations: a method to grade keratoconus.

PURPOSE: To use the anterior corneal surface higher order aberrations as a tool to detect and grade keratoconus using corneal map analysis videokeratoscopy. METHODS: A prospective observational comparative study of 80 eyes was performed. The eyes were divided into two groups. Group A comprised 40 eyes of 20 asymptomatic individuals with no ocular pathology. Mean sphere was -0.03 diopters (D) (range: +0.75 to -0.75 D), mean cylinder was -0.27 D, mean average K was 43.28 D, and mean uncorrected visual acuity (UCVA) was 1.01. Group B comprised 40 eyes of 25 patients with keratoconus. Mean sphere was -3.70 D (range: +2.00 to -10.00 D), mean cylinder was -3.82 D, mean average K was 49.29, and mean best spectacle-corrected visual acuity (BSCVA) was 0.61. RESULTS: In group A, mean root-mean-square (RMS) of spherical (Z4 and Z6), coma-like (Z3, Z5, and Z7), and higher order aberrations (Z3-7) were 0.38 microm, 0.35 microm, and 0.52 microm, respectively. In group B, mean RMS of spherical, coma-like, and higher order aberrations were 1.06 microm, 2.90 microm, and 3.14 microm, respectively, for a 6.0-mm simulated pupil diameter. Mean RMS differences between the two groups were 0.68 microm (P < or = .0002), 2.55 microm (P < or = .0001), and 2.61 microm (P < or = .0001) for spherical, coma-like, and total higher order aberrations, respectively. In group B, according to Amsler-Krumeich classification, the mean RMS of coma-like aberration was 1.87 microm in grade I (14 eyes), 2.97 microm in grade II (11 eyes), 3.46 microm in grade III (12 eyes), and 5.20 microm in grade IV (3 eyes). CONCLUSIONS: Corneal higher order aberrations, especially coma-like aberrations, are significantly higher in eyes with keratoconus than normal eyes. Coma-like aberrations, with the aid of a corneal aberrometry map, are good indicators for early detection and grading of keratoconus.

Adult↗