Stage-Related Therapy of Corneal Dystrophies

Abstract

Corneal dystrophies typically result in a gradual bilateral loss of vision in a primary 'white eye' - often in conjunction with epithelial defects in later stages. Treatment of corneal dystrophies needs to be stage-related. To ensure a stage-related therapeutic approach, an adequate classification based on clinical, histopathological and genetic knowledge is indispensable. In principle, topical medications, contact lenses and various microsurgical approaches are applicable. In case of predominantly superficial dystrophies of the epithelium, basal membrane and/or Bowman's layer (map-dot-fingerprint, Meesmann, Lisch, Reis-Bücklers, Thiel-Behnke), recurrent epithelial defects may complicate the clinical picture. If conservative therapy with gels/ointments, application of therapeutic contact lenses and/or conventional corneal abrasion are not successful, phototherapeutic keratectomy (PTK) using a 193-nm excimer laser is the method of choice today. PTK can be repeated several times, thus post poning corneal transplantation (lamellar or even penetrating) for a long time. Three major goals may be achieved by PTK depending on the diagnosis: (1) to remove superficial opacities; (2) to regularize the surface and treat irregular astigmatism, and (3) to improve the adherence of the epithelium. In dystrophies with depositions predominantly in the stroma (e.g. granular, lattice, macular, recurrence on the graft), PTK may be a reasonable alternative to anterior lamellar or penetrating keratoplasty (PKP) depending on the exact localization of the lesions. Besides exact determination of the depth of depositions using a slit lamp, a preoperative topography analysis is indispensable. The therapy of endothelial dystrophies depends on diagnosis and age: Fuchs endothelial corneal dystrophy will need corneal transplantation (e.g. when visual acuity drops below 0.4). In contrast, transplantation will only be very rarely necessary in posterior polymorphous corneal dystrophy, but the intraocular pressure has to be checked frequently. Especially in elderly patients with reduced compliance, posterior lamellar keratoplasty - preferably in the form of Descemet stripping automated endothelial keratoplasty - may be performed instead of PKP. In case of congenital hereditary endothelial dystrophy, the best time point of PKP has to be determined with regard to amblyopia (surgery too late) and inadequate follow-up (surgery too early) together with parents and pediatric ophthalmologists on an individual basis. In conclusion, for stage-related therapy of corneal dystrophies, besides contact lenses, PTK and PKP, various techniques of lamellar keratoplasties represent an indispensable enrichment of our corneal microsurgical spectrum today.

Therapeutische Excimerlaserchirurgie der Hornhaut

“…Idealerweise sollte auch zwischen klinisch signifikanten und klinisch nicht signifikanten Rezidiven unterschieden werden [21,22]. Wichtige Informationen zum klinischen Bild, der Lokalisation und der Rezidivhäufigkeit können der neuen Einteilung der Dystrophien entnommen werden [23,24]. Der Erfolg oder Misserfolg einer PTK bei Hornhautdystrophien wird entscheidend von der Tiefenausdehnung der Ablagerungen im Stroma und der zielgerichteten Ablation mitbestimmt.…”

“…Zu bedenken und insbesondere im Aufklärungsgespräch zu vermitteln ist der häufig rezidivierende Charakter der Dystrophie. Abhängig von der Lokalisation der Pathologie ist mit einer frühen (epithelial) oder verzögerten (stromalen) Rezidivität zu rechnen [23,28]. Aufgrund einer starken Rezidivneigung bzw.…”

Clinical anatomy of the anterior chamber angle in congenital aniridia and consequences for trabeculotomy/cyclophotocoagulation

“…Congenital aniridia is a severe malformation (K € asmann-Kellner and Seitz et al, 2014) of the anterior segment ( Fig. 1) involving the posterior segment (giant retinal tears, foveal hypoplasia and optic nerve head dysplasia, glaucomatous optic nerve atrophy).…”

“…Iris remnants or a small iris stump can cover the anterior chamber angle forming anterior synechia. This angle closure is a potential cause of increasing intraocular pressure (Grant and Walton, 1974;Seitz et al, 2014). Without topical or surgical therapy these eyes will go blind .…”

“…Without topical or surgical therapy these eyes will go blind . The visibility of the anterior chamber angle can be compromised because of corneal vascularization, limbal stem cell insufficiency, and subepithelial fibrosis Seitz et al, 2014;K € asmann-Kellner et al, 2015).…”