Effect of accelerated corneal crosslinking on ocular response analyzer waveform-derived parameters in progressive keratoconus / Efeito do crosslimking corneano acelerado nos parâmetros derivados da forma de onda do analisador de resposta ocular no ceratocone progressivo

ABSTRACT Purpose: To evaluate the effect of accelerated corneal crosslinking on corneal biomechanics with an ocular response analyzer in patients with progressive keratoconus. Methods: In this retrospective study, 50 eyes of 45 patients with progressive keratoconus who underwent accelerated corneal crosslinking were evaluated with ocular response analyzer waveform parameters before and one year after corneal crosslinking. Paired two-tailed Student's t-test was performed to compare the parameters before vs. after corneal crosslinking. Results: Mean patient age was 17.6 ± 3.6 (range 9-25) years. A significant increase was observed in p1 area, p2 area, h2, and dive2 values. No significant difference in corneal hysteresis, corneal resistance factor, or other waveform-derived parameters was observed at one year postoperatively. Conclusion: For estimating the effect of accelerated corneal crosslinking on corneal biomechanics, parameters such as p1 area, p2 area, h2, and dive2 are more sensitive than corneal hysteresis and corneal resistance factor. These results may help us to find out which corneal crosslinking method is most effective for stiffening the cornea.

RESUMO Objetivo: Avaliar o efeito do cross-linking corneano acelerado na biomecânica corneana com analisador de resposta ocular em pacientes com ceratocone progressivo. Métodos: Neste estudo retrospectivo, 50 olhos de 45 pacientes com ceratocone progressivo submetidos à cross-linking corneano acelerado foram avaliados com os parâmetros da forma de onda do analisador de resposta ocular antes e um ano após o tratamento com cross-linking corneano. O teste t de Student pareado bicaudal foi realizado para comparar os parâmetros antes e depois do cross-linking corneano. Resultados: A média de idade dos pacientes foi de 17,6 ± 3,6 (variação de 9 a 25) anos. Um aumento significativo foi observado nos valores de p1area, p2area, h2 e dive2. Nenhuma diferença significativa foi encontrada na histerese da córnea, fator de resistência da córnea ou outros parâmetros derivados da forma de onda foi observada em um ano de pós-operatório. Conclusão: Para estimar o efeito do cross-linking corneano acelerado na biomecânica corneana, parâmentros como p1area, p2area, h2 e dive2 são mais sensíveis que histerese da córnea e fator de resistência corneana. Esses resultados podem nos ajudar a descobrir qual método cross-linking corneano é mais eficaz no enrijecimento da córnea.

Effect of accelerated corneal crosslinking on ocular response analyzer waveform-derived parameters in progressive keratoconus.

PURPOSE: To evaluate the effect of accelerated corneal crosslinking on corneal biomechanics with an ocular response analyzer in patients with progressive keratoconus. METHODS: In this retrospective study, 50 eyes of 45 patients with progressive keratoconus who underwent accelerated corneal crosslinking were evaluated with ocular response analyzer waveform parameters before and one year after corneal crosslinking. Paired two-tailed Student's t-test was performed to compare the parameters before vs. after corneal crosslinking. RESULTS: Mean patient age was 17.6 ± 3.6 (range 9-25) years. A significant increase was observed in p1 area, p2 area, h2, and dive2 values. No significant difference in corneal hysteresis, corneal resistance factor, or other waveform-derived parameters was observed at one year postoperatively. CONCLUSION: For estimating the effect of accelerated corneal crosslinking on corneal biomechanics, parameters such as p1 area, p2 area, h2, and dive2 are more sensitive than corneal hysteresis and corneal resistance factor. These results may help us to find out which corneal crosslinking method is most effective for stiffening the cornea.

Applications of different types of gas-permeable contact lenses in keratoconus and their visual results.

PURPOSE: To show applications of different types of gas-permeable contact lenses in patients with keratoconus and to compare visual acuity (VA) results. METHODS: A total of 229 eyes of 133 patients who used different types of rigid gas-permeable contact lenses between April 2003 and April 2010 at the Cornea and Contact Lens Unit of Eye Clinic 2 of the Ministry of Health, Ulucanlar Eye Training and Research Hospital, were included. Visual acuity of patients was classified as uncorrected and corrected with eyeglasses and corrected with contact lenses. The patients were compared in terms of VA, daily contact lens wear time, and complications. RESULTS: A total of 70 out of 133 (52.6%) patients in our study were male, and 63 (47.4%) were female. The mean age was 25.9 ± 7.03 years (12-45). As for the classification of the 229 eyes included in the study, 136 of 229 (59.4%) eyes had moderate keratoconus, 88 (38.4%) had advanced keratoconus, and 5 (2.2%) had severe keratoconus. Following the contact lens application, the VA in all patients increased when compared to uncorrected and corrected with eyeglasses groups and the difference was statistically significant (p<0.005). When a comparison of different types of contact lenses was made, a statistically significant difference was not found (p>0.5) in terms of increase in VA. When patients were evaluated in terms of contact lens wear times, it was observed that Boston Equalens II was preferred by patients wearing lenses 4-8 hours/day. For patients wearing lenses more than 8 hours a day, Rose K lens was used the most. No serious complication was observed in any of the patients that would lead them to stop wearing contact lenses during the follow-up period. There was also no need for keratoplasty in any patient during the follow-up period. CONCLUSIONS: We detected an increase in VA in patients with rigid contact lenses. In addition, some contact lenses were better tolerated by patients and were used for a longer time during the day.

Optic disc and retinal nerve fiber layer parameters of eyes with keratoconus.

BACKGROUND AND OBJECTIVE: To evaluate optic nerve head (ONH) characteristics and retinal nerve fiber layer (RNFL) thickness measurements in patients with nonglaucomatous keratoconus. PATIENTS AND METHODS: This was a cross-sectional, observational study in which 46 patients with keratoconus and 74 healthy subjects were included. Analysis of ONH and RNFL imaging were performed by confocal scanning laser ophthalmoscopy and optical coherence tomography, respectively. RESULTS: Eyes with keratoconus had larger disc area (2.37 ± 0.5 vs 2.17 ± 0.36 mm(2)) (P = .013), larger cup area (0.65 ± 0.53 vs 0.49 ± 0.28 mm(2)) (P = .035) and deeper cup depths (for mean cup depth 0.24 ± 0.09 vs 0.20 ± 0.07 mm, P = .008 and for maximum cup depth 0.69 ± 0.27 vs 0.60 ± 0.17 mm, P = .037) than control group eyes. Height variation contour also differed in the two groups (P = .007) but RNFL measurements did not. CONCLUSION: RNFL thickness between patients with keratoconus and healthy subjects seems to be more comparable than ONH parameters.

The effect of contact lens usage on corneal biomechanical parameters in myopic patients.

PURPOSE: To determine and compare the corneal biomechanical properties in myopic patients who use contact lenses and those who do not use contact lenses. METHODS: The study consisted of 56 myopic patients who used contact lenses (study group) and 123 myopic patients who did not use contact lenses (control group). Intraocular pressure (IOP) was measured with an ocular response analyzer (ORA) and a Goldmann applanation tonometer. Central corneal thickness was measured with an ultrasonic pachymeter. Axial length and anterior chamber depth measurements were acquired with contact ultrasound A-scan biometry. The differences in ORA parameters between study and control group participants were analyzed. RESULTS: The mean corneal hysteresis in study and control groups was 10.1 ± 1.6 mm Hg (6.5-15.9 mm Hg) and 9.7 ± 1.5 mm Hg (6.3-14.2 mm Hg), respectively (P = 0.16). The mean corneal resistance factor was 10.4 ± 1.9 mm Hg (4.6-15.5 mm Hg) in the study group compared with 9.6 ± 1.9 mm Hg (5.1-15.0 mm Hg) in the control group. The difference for corneal resistance factor was statistically significant (P = 0.014). There was no significant difference in corneal-compensated IOP (P = 0.24). Mean Goldmann-correlated IOP was significantly higher in the study group than in control subjects (15.8 ± 3.2 vs. 14.7 ± 3.7 mm Hg) (P = 0.044). None of the corneal biomechanical parameters was significantly correlated to duration of contact lens usage in the study group. CONCLUSIONS: Our results suggest that ORA-generated parameters may be different in subjects with and without contact lens usage. Further longitudinal studies need to be performed to establish the relevance of our results.

A comparative study of tissue glue and vicryl suture for closing limbal-conjunctival autografts and histologic evaluation after pterygium excision.

PURPOSE: To compare clinical and histopathologic outcomes of tissue glue and vicryl suture to attach limbal conjunctival autografts in pterygium surgery. METHODS: Twenty-four eyes of 24 patients were included in this study. All eyes had primary pterygia and were treated with limbal conjunctival autograft transplantation after pterygium resection. Tissue glue (Tisseel) was used to attach the limbal conjunctival autograft in 12 eyes and vicryl sutures in 12 eyes. Patients were followed for 6 months. Histopathologic examination was performed in both groups on postoperative days 1, 15, and 45. Main outcome measures were patient comfort, graft success, complications, histopathologic evaluation, and recurrence of pterygium. RESULTS: Patient comfort was significantly higher in the tissue glue group than the vicryl suture group (P < 0.05). All grafts were intact in both groups during the follow-up period. No recurrence was observed during the 6-month follow-up in both groups. Foreign-body granulation tissue was not seen in any histopathologic studies in eyes with tissue glue, whereas it was observed in eyes with vicryl sutures from day 15 to day 45. The tissue glue was seen under the conjunctiva on the first postoperative day and was not seen on days 15 and 45. CONCLUSIONS: Our results showed that limbal conjunctival autografting is an effective surgical technique for the treatment of pterygium, and tissue glue was efficacious in securing the limbal conjunctival autograft in pterygium surgery. The use of tissue glue decreases patient symptoms during the postoperative period after pterygium surgery. Compared with sutures, tissue glue had no adverse effects on ocular tissue.

Does blunt ocular trauma induce corneal astigmatism?

PURPOSE: To determine the effect of blunt ocular trauma on refractive astigmatism. METHODS: Eighty-six eyes of 86 patients with known previous refractive status exposed to blunt ocular trauma were included in the study. Trauma-induced astigmatism (TIA) was calculated using vector analysis. In eyes with TIA, central corneal thickness was assessed by ultrasound pachymetry, and corneal topographies were obtained. Anterior-chamber angles were examined by Goldmann 3-mirror lens to find microhemorrhages, scarring, or recession. Patients were followed up between 8 and 12 months (average, 9.2 months). RESULTS: In 18 eyes (21%), TIA was detected. Six (7%) of these eyes had lenticular astigmatism caused by traumatic lens subluxation. In the remaining 12 eyes (14%), corneal topography showed regular astigmatic patterns, which were symmetrical in 3 eyes and asymmetric in the remaining 9. The etiologic factor was a game marble in 6 eyes and a stone in the remaining 6. The mean central corneal thickness was 535.75 microm (range, 498-570 microm) in these 12 eyes. In 9 of these 12 eyes, recession or scarring in the anterior-chamber angle was detected at 1 edge of the steepest axis. CONCLUSIONS: Blunt trauma can induce astigmatism. Hard and small objects are more likely to induce astigmatism.

Monocular temporal hemianopia in a young patient.

A 12-year-old girl presented with a history of sudden visual hemi-field loss in the left eye. The visual field defect was a clear-cut temporal hemianopia in the left eye; eye was normal. Complete eye examination and neuro-imaging of brain and opto-chiasmal region revealed normal structural findings. The visual field defect was suspected to be non-organic. This assumption was proven to be the diagnosis when simultaneous binocular fields showed the same pattern, although the contralateral eye's nasal hemi-field was intact. This symptom was alleviated by reassurance and placebo treatment.

Lower lid retraction: a valuable finding in juvenile Graves' orbitopathy.

PURPOSE: To evaluate the findings of juvenile Graves' orbitopathy. SUBJECTS AND METHODS: Retrospective evaluation of our patients with Graves' disease who are younger than 16 years. RESULTS: Seventeen patients younger than 16 years were identified among 138 patients who were being treated for hyperthyroidism and goiter. Eleven (64.7%) of them had lid findings, orbital findings, or both and constituted 8.8% of the total of 125 such patients. Ophthalmic signs were common and were among the presenting signs in children with Graves' disease. Orbitopathy was mild and was more frequent in girls. Lower lid retraction and lag (ie, hesitation of the lower lids to follow upgaze) appeared to be constant and early findings. CONCLUSION: Ophthalmologists and pediatricians should be aware of and look for lid signs in children presenting with related complaints and a history suggesting hyperthyroidism, goiter, or both.