Excimer laser phototherapeutic keratectomy in eyes with anterior corneal dystrophies: short-term clinical outcomes with and without an antihyperopia treatment and poor effectiveness of ultrasound biomicroscopic evaluation.
OBJECTIVE
To evaluate the use of high-frequency ultrasound biomicroscopy (UBM) in determining the depth of corneal pathology in eyes undergoing excimer laser phototherapeutic keratectomy (PTK) for primary or recurrent anterior stromal corneal dystrophies. Corneal clarity, visual acuity, and refractive changes in eyes with and without an antihyperopia treatment were also analyzed.


METHODS
Twenty eyes of 14 patients with anterior stromal corneal dystrophies were treated with PTK. Eyes were evaluated pre- and 6-8 weeks postoperatively with slit-lamp biomicroscopy, manifest refraction, keratometry, computerized corneal topography, ultrasound pachymetry, and UBM.


RESULTS
Nineteen of 20 corneas (95%) had greatly improved corneal clarity after PTK. Mean uncorrected Snellen vision improved from 20/102 to 20/69, and best corrected vision improved from 20/62 to 20/38. Nine eyes (45%) improved two or more lines of uncorrected vision, and 13 eyes (65%) improved two or more lines of best corrected vision. Mean change in spherical equivalent was just -0.92 diopters (SD 4.3 diopters); however, the range was large (-13 to +3.88 diopters). UBM measurement of central corneal pathology did not correlate significantly with the actual PTK ablation depth (P = 0.07). The amount of antihyperopia treatment did not correlate with changes in manifest refraction spherical equivalent, keratometry, or computerized corneal topography readings but did correlate with length of time until corneal reepithelialization after PTK (P = 0.003).


CONCLUSIONS
PTK resulted in improvements in corneal clarity and visual acuity in most patients with superficial corneal stromal dystrophies. UBM was not an effective tool to accurately measure the depth of corneal pathology preoperatively. The combined approach of minimizing ablation depth and selective use of an antihyperopia treatment resulted in minimal mean change in spherical equivalent; however, the range was large. PTK is a very good minimally invasive technique to improve vision in eyes with anterior stromal corneal dystrophies.
Rapuano
Christopher J
CJ
Cornea Service, Wills Eye Hospital, Department of Ophthalmology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA. cjrapuano@willseye.org
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003317:Corneal Dystrophies, Hereditary / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D003319:Corneal Stroma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D019781:Corneal Topography; D019573:Epithelium, Corneal / Q000502:physiology; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D018903:Photorefractive Keratectomy / Q000379:methods*; D012029:Refraction, Ocular; D016896:Treatment Outcome; D014463:Ultrasonography; D014792:Visual Acuity; D014945:Wound Healing