Additional Applications of Corneal Cross Linking

Corneal collagen cross-linking (CxL) is a prevalent surgical method for the management of keratoconus. However, literature suggests that, further to keratoconus, CxL has a beneficial impact on a series of corneal related diseases and states

Pseudophakic Presbyopic Corrections

Presbyopia is a prevalent productivity-reducing, age-related visual disorder that results in a progressive near vision impairment. Conventional treatment modalities (ie. presbyopic spectacles or contact lenses) are associated with poor acceptance, productivity loss and negative impact on life quality. However, a variety of surgical methods are available to address presbyopia; among them, multifocal and multifocal toric intraocular lenses (IOLs) and monovision techniques. For the best possible refractive outcomes, the overall management of presbyopic patients is necessary. Specifically, patient selection according to personality and daily activities, topography, aberrometry, astigmatism, pupil and fundus assessment, ophthalmic surface, and premium lens selection should be taken into consideration. Additionally, image-guided surgery could increase the accuracy in multifocal/multifocal toric IOL implantation, and optimize the refractive outcome increasing patient satisfaction. Primary objective of this chapter is to analyze the fundamental preoperative, intraoperative and postoperative management of patients that undergo pseudophakic presbyopic corrections with conventional or digital-marking assisted techniques

Psychometric properties of the Greek version of the NEI-VFQ 25

<p>Abstract</p> <p>Background</p> <p>To evaluate the reliability and construct validity of a Greek version of the NEI-VFQ-25 in patients with chronic ophthalmic diseases.</p> <p>Methods</p> <p>We developed the Greek version of the instrument using forward and backward translation. One hundred-eighty-six patients responded to the questionnaire. To examine reliability, Cronbach's alpha for each subscale was used as an index of internal consistency. Test-retest reliability was evaluated with intraclass correlation coefficients. Regarding construct validity, both convergent and discriminant validities were calculated by means of multi-trait analysis. Rasch analysis was used to estimate the visual ability required by each item for a particular response, and each patient's visual ability. Correspondingly, instrument validity was evaluated by estimating the distribution of residuals for item and subject measures.</p> <p>Results</p> <p>Four patient groups were studied, each including participants with a single cause of visual impairment. Group 1 consisted of 84 glaucoma subjects. Group 2 included 30 subjects with age-related macular degeneration (ARMD); group 3 included 25 subjects with dry-eye syndrome, whereas group 4 included 18 cataract patients. Twenty-nine healthy individuals comprised the control group. NEI-VFQ scores (mean ± SD) for the glaucoma, ARMD, dry-eye, cataract and control groups were: 76.9 ± 20.2, 70.9 ± 20.2, 81.6 ± 16.5, 73.5 ± 24.0 and 93.7 ± 8.9 respectively. Item analysis revealed no significant data skewing. Cronbach's alpha ranged from 0.678 to 0.926, with most subscales having high internal consistency. Intraclass correlation coefficient ranged from 0.717 to 0.910 for all subscales. All items passed the convergent and discriminant validity tests. Strong correlations were detected between visual acuity and "general vision", "distant activities" and "near activities" subscales. Significant correlations were also detected between visual field deficits and the "peripheral vision" and "general vision" subscales. Rasch analysis revealed potential weaknesses of the instrument that are associated with the assumptions of the model itself. Specifically, low precision of the "agreement" items was detected in the estimation of visual ability. Twenty-three percent of the subjects had fit statistics that fell outside the tolerance box.</p> <p>Conclusion</p> <p>Although traditional validation methods indicated that the Greek version of the NEI-VFQ-25 is a valid and reliable instrument for VS-QoL assessment, Rasch analysis detected significant misfits to the model, especially of the "agreement" items. This means that results of the corresponding subscales should be interpreted with extreme caution.</p

Association between isotretinoin use and central retinal vein occlusion in an adolescent with minor predisposition for thrombotic incidents: a case report

<p>Abstract</p> <p>Introduction</p> <p>We report an adolescent boy with minimal pre-existing risk for thromboses who suffered central retinal vein occlusion associated with isotretinoin use for acne. To the best of our knowledge, this is the first well documented case of this association.</p> <p>Case presentation</p> <p>An otherwise healthy 17-year-old white man who was treated with systemic isotretinoin for recalcitrant acne was referred with central retinal vein occlusion in one eye. Although a detailed investigation was negative, DNA testing revealed that the patient was a heterozygous carrier of the G20210A mutation of the prothrombin gene. Despite the fact that this particular mutation is thought to represent only a minor risk factor for thromboses, it is probable that isotretinoin treatment greatly increased the risk of a vaso-occlusive incident in this patient.</p> <p>Conclusion</p> <p>Isotretinoin use may be associated with sight- and life-threatening thrombotic adverse effects even in young patients with otherwise minimal thrombophilic risk. Physicians should be aware of such potential dangers.</p

Corneal melting after collagen cross-linking for keratoconus: a case report

<p>Abstract</p> <p>Introduction</p> <p>Corneal collagen cross-linking is a rather new technique that uses riboflavin and ultraviolet A light for collagen fiber stabilization in keratoconus corneas. Other than reversible side effects, the preliminary results of corneal collagen cross-linking studies suggest that it is a rather safe technique. In this report, we demonstrate a case of corneal melting after corneal collagen cross-linking for keratoconus corneas associated with an acute inflammatory response.</p> <p>Case presentation</p> <p>A 23-year-old Caucasian man with keratoconus cornea stage 1 to 2 underwent uneventful corneal collagen cross-linking treatment according to the Dresden protocol. The next day the patient had intense photophobia, watering and redness of the eye, and his visual acuity was limited to counting fingers. Slit lamp biomicroscopy revealed severe corneal haze accompanied by non-specific endothelial precipitates following an acute inflammatory response. Mild inflammation could be detected in the anterior chamber. Moreover, the re-epithelialization process could barely be detected. His corneal state gradually deteriorated, resulting in descemetocele and finally perforation.</p> <p>Conclusion</p> <p>In this report, we present a case of a patient with corneal melting after standard corneal collagen cross-linking treatment for keratoconus corneas following an acute inflammatory response. Despite modifying postoperative treatment, elaboration of all apparent associated causes by the treating physicians and undergoing extensive laboratory testing, the patient developed descemetocele, which led to perforation. Our report suggests that further research is necessary regarding the safety of corneal collagen cross-linking in keratoconus corneas.</p