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Abstract Background Macular corneal dystrophy is a rare inherited disease of the cornea leading to deposits mainly in the stroma. Affected patients suffer from progressive loss of visual acuity which should be treated with penetrating keratoplasty. This is the first case report describing the clinical and histopathological findings of corneal tissue after failed phototherapeutic keratectomy (PTK) in a patient with macular corneal dystrophy. Case presentation A 32-year-old man presented with visual impairment, blurred vision and increasing glare sensitivity in both eyes in 2014. All symptoms had existed for several years and had recently increased sharply. A corneal dystrophy was diagnosed and penetrating keratoplasty was recommended but the patient was hesitant to undergo surgery. In 2018, in contrast to current guidelines, a PTK was performed in both eyes in Turkey for unknown reasons. In May 2019, he presented again in our clinic. Best corrected visual acuity was markedly reduced in both eyes. Slit-lamp examination revealed multiple dense, poorly circumscribed grey-white patchy changes in the stroma accompanied by corneal opacity in both eyes. In February 2020, the patient decided to have penetrating keratoplasty performed at the University Eye Hospital in Tübingen. The explanted cornea was stained for acid mucopolysaccharides (AMP) and periodic acid–Schiff staining (PAS). The histopathological examination revealed destruction of Bowman’s layer and a subepithelial fibrosis band due to the PTK previously performed. The AMP staining demonstrated blue deposits typical of macular corneal dystrophy, mainly in the stroma but also in the endothelium. Interestingly, the acidic mucopolysaccharides were found increased in the PTK-induced subepithelial fibrosis band. The postoperative course after keratoplasty was favourable with a significant increase in visual acuity and a clear graft. Conclusions This report presents the first case of a histologically evident exacerbation of macular corneal dystrophy after PTK and emphasizes the relevance of thorough pre-interventional diagnosis and patient selection to consider other therapeutic approaches, such as penetrating keratoplasty.

Abstract Background This study aimed to analyze if the outcome after corneal crosslinking (CXL) in progressive keratoconus patients depends on the stage at which the procedure is performed. This knowledge would help to improve success of CXL and to define surgery indications in those patients. Methods In this retrospective study, 124 consecutive eyes of 100 patients with progressive keratoconus undergoing corneal CXL at the University Eye Hospital Tübingen were included. The eyes were graded according to modified Krumeich stages depending on induced myopia or astigmatism, corneal radii, minimum corneal thickness, and morphological changes. The observation period covered November 2008 to September 2018. Preoperatively, 12 and 24 months after CXL, the best corrected visual acuity (BCVA) was determined and astigmatism as well as tomographic parameters (Kmax, Kmin, central corneal thickness (CCT), minimum corneal thickness (MCT)) were measured by means of a Scheimpflug camera system. Results BCVA results showed significant differences between the modified Krumeich stages at 12 months (p = 0.014) and at 24 months postoperatively (p = 0.032). Also, astigmatism differed significantly among the stages at 24 months after CXL (p = 0.023). However, no significant differences regarding astigmatism were detectable after 12 months. In terms of Kmax, Kmin, CCT, and MCT, no significant differences between the Krumeich stages were observed. Conclusions BCVA showed a significantly higher improvement after CXL in the early stage of keratoconus compared to a higher stage. However, the postinterventional tomographic values did not differ significantly between the different modified Krumeich stages. The significantly higher improvement in BCVA after CXL in the early stage might indicate that earlier intervention provides a higher subjective benefit to the individual. Further studies with larger sample sizes are needed to confirm these findings.