By studying the effects of different protocols of corneal collagen cross-linking on visual, refractive and tomographic parameters in patients with progressive keratoconus, researchers determined that patients who received accelerated cross-linking with irradiations of 30 mW/cm2 for three minutes fared worse at the end of 12 months than conventional cross-linking or accelerated cross-linking of 9 mW/cm2 for 10 minutes or 18 mW/cm2 for five minutes.
In the study, 138 eyes of 138 patients with progressive keratoconus underwent corneal collagen cross-linking. Following detailed preoperative examination, Group I (n=36) underwent conventional cross-linking (3 mW/cm2 for 30 minutes); Group II (n=36), Group III (n=33) and Group IV (n=33) each underwent accelerated cross-linking (Group II: 9 mW/cm2 for 10 minutes; Group III: 18 mW/cm2 for five minutes; Group IV: 30 mW/cm2 for three minutes). Changes in corrected distance visual acuity, spherical equivalent, flat keratometry, steep keratometry, thinnest pachymetry, specular microscopy and demarcation line were studied at six and 12 months.
Improvement in the mean CDVA and SE was seen in all groups at the one-year follow-up period. However, the improvement seen in Group IV (p=0.15 at six months; p=0.17 at 12 months) was not statistically significant when compared with the other groups. Likewise, Group III (p=0.01 at six and 12 months) showed the best results among all groups. Flattening of steep and flat keratometry was significant in Groups I (p=0.01) and II (p=0.01) as compared to the other groups. There was no significant difference in the pachymetry or specular microscopy in any of the groups. Groups I and II demonstrated a good demarcation line when compared to other groups. Groups I, II and III showed better visual, refractive and tomographic improvements at the end of the 12 months.
Am J Ophthalmol 2015;160:243-249.
Shetty R, Pahuja N, Nuijts R, Ajani A, et al.
Refractive Outcomes of Triple DMEK with Cataract Surgery
A retrospective case series including patients with Fuchs’ endothelial dystrophy and cataract without coincident pathology found that triple Descemet’s membrane endothelial keratoplasty safely achieved excellent corrected distance visual acuity.
Researchers evaluated the outcomes of 108 sequential triple DMEK procedures, including the use of toric IOLs in select cases. Within the mean follow-up of 11.9 months, the median CDVA was 20/20 (range: 20/15 to 20/40) and the median uncorrected distance visual acuity in eyes with a distance target (n=84) was 20/40 (r: 20/20 to 20/200). Additionally, 45 percent of patients gained three or more lines of CDVA.
The median refractive error was +0.43 D (interquartile range: -0.34 to +1.17 D). Aspheric intraocular lenses (n=91) did not significantly change refractive astigmatism (mean: preoperative +0.926 ±0.144 D [SD]; postoperative +0.945 ±0.129 D; p=0.83), while toric IOLs (n=9) did (mean: preoperative +2.47 ±0.36 D; postoperative: +0.94 ±0.90 D; p=0.0015). The anterior curvature measured by Scheimpflug imaging (Pentacam) did not significantly change (mean: -0.06 ±0.47 D; p=0.41); however, keratometry by partial coherence interferometry (IOLMaster) did (mean -0.6 ±0.9 D; p<0.0001).
The selection of the optimum IOL power is complicated by several factors. Because Fuchs’ dystrophy induces changes predominately in the central cornea, measurements averaging curvature over a larger area might underreport significant refractive deviations. In the absence of an algorithm to more precisely individualize IOL calculations, a refractive target of -0.75 to -1 D will help reduce the proportion of eyes left hyperopic.
J Cataract Refract Surg 2015; 41:1182-1189.
Schoenberg E, Price Jr. F, Miller J, McKee Y, Price M.