July 11, 2015
Corneal transplantation techniques for the treatment of endothelial diseases have evolved quickly from full-thickness penetrating keratoplasty (PK) to partial-thickness endothelial keratoplasty procedures, including deep lamellar endothelial keratoplasty (DLEK) and Descemet stripping endothelial keratoplasty (DSEK).
Endothelial keratoplasty offers corneal surgeons simpler postoperative management, including lack of suture removal and suture-associated complications, a predictable postoperative refractive error, and a tectonically stronger globe.
Although there are no published randomized controlled trials that compare DSEK and PK to establish definitively whether DSEK results in better vision and graft survival, and despite many patients being unable to attain a visual acuity of 20/20 after DSEK, the technique has become the procedure of choice for corneal endothelial disease.
"The management advantages of DSEK over PK from the surgeon's perspective are well-known," says Sanjay V. Patel, M.D., an ophthalmologist at Mayo Clinic's campus in Rochester, Minnesota, "but little is known about the impact of EK on patient-reported outcomes."
Results of a study by Dr. Patel and a research team at Mayo Clinic to assess vision-related quality of life in Fuchs' dystrophy and changes in vision-related quality of life after three types of keratoplasty — PK, DLEK and DSEK — were published in Ophthalmology in 2014.
Fuchs' dystrophy is a slowly progressive disease that typically affects both eyes symmetrically, resulting in impaired visual function with decreased visual acuity and increased disability glare. Patients who required their ﬁrst keratoplasty in either eye because of decreased vision caused by Fuchs' dystrophy were recruited from the Mayo Clinic cornea service. Of 63 subjects, 12 (12 eyes) received PK, 11 (11 eyes) received DLEK and 40 (40 eyes) received DSEK. All subjects were enrolled in two consecutive prospective studies.
In the ﬁrst study, subjects were randomized to PK or DLEK between 2004 and 2006 and examined prospectively through three years after surgery. Entrance best-corrected visual acuity was 20/40 (Snellen equivalent) or worse, and only subjects with a recipient diagnosis of Fuchs' dystrophy were included.
In the second study, subjects with Fuchs' dystrophy were prospectively examined through three years after DSEK. Enrollment occurred between 2006 and 2009, and there was no entrance visual acuity criterion.
Corneal surgeons performed PK with a recipient diameter of 7.5 or 7.75 mm (mean, 7.55 mm), with the donor secured to the host using a double-running suture technique. DLEK was performed through a 9- to 10-mm scleral tunnel incision initiated at a depth of 350 mm. DSEK was performed through a 5- to 6-mm temporal scleral tunnel incision and inserted in the donor by using a folding technique. For phakic eyes, cataract extraction and intraocular lens insertion were performed simultaneously.
The following outcomes were determined at examinations before keratoplasty and at regular intervals through three years after keratoplasty:
- Vision-related quality of life was assessed using the 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25)
- Best spectacle-corrected and uncorrected visual acuities were measured by using the electronic Early Treatment Diabetic Retinopathy Study protocol
- Keratometric cylinder was measured by a manual keratometer
- Disability glare was measured with a straylight meter
Scores improve for all treatments
The composite score for all eyes with Fuchs' dystrophy before keratoplasty was 72 ± 11 (n = 63) and did not differ between eyes destined for PK, DLEK or DSEK (P = 0.88).
Vision-related quality-of-life composite scores improved by six months with all treatments when compared with preoperative (PK, P = 0.008; DLEK, P = 0.03; DSEK, P < 0.001), with continued improvement between six months and three years after PK (P = 0.01) and DSEK (P = 0.004). At six months, the composite score was higher after DSEK than after PK (P = 0.006).
At three years, there were no differences in composite scores between the three treatments. The mean composite score for all three was 90 (P = 0.33).
"Vision-related quality of life in all patients with Fuchs' dystrophy improved after corneal transplantation," says Dr. Patel. "Although all three keratoplasty techniques examined resulted in similar improvement over the ﬁrst three postoperative years, improvement was fastest after DSEK and slowest after PK, which may be explained in part by rapid improvement in uncorrected visual acuity. Best-corrected visual acuity after DSEK frequently improves close to that of subjects with normal vision, indicating that other aspects of visual function are important for overall function."
For more information
Trousdale ER, et al. Vision-related quality of life before and after keratoplasty for Fuchs' endothelial dystrophy. Ophthalmology. 2014;121:2147.
Mayo Clinic. A comparison between full thickness and partial thickness corneal transplantation for corneal edema. ClinicalTrials.gov.