Large-diameter deep anterior lamellar keratoplasty for keratoconus: visual and refractive outcomes.
BACKGROUND
To investigate the difference in clinical outcomes between large-diameter deep anterior lamellar keratoplasty (L-DALK) and standard DALK (S-DALK) for the treatment of keratoconus.


METHODS
132 patients (132 eyes) from the Zhongshan Ophthalmic Center with a clinical diagnosis of keratoconus were enrolled. The participants were featured by the intolerance to rigid gas-permeable contact lenses or unsuccessful fitting of contact lenses. Using stratified blocked randomisation, eligible eyes were allocated into the L-DALK group or the S-DALK group (66 eyes, respectively). Postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractive sphere, manifest cylinder and spherical equivalent refractive error were tested at 6, 12, 18 and 24 months after surgery.


RESULTS
After surgery, the L-DALK group had better UCVA and BSCVA than the S-DALK group (p=0.000 and 0.021, respectively). At 24 months, mean BSCVA was 0.17±0.10 logarithm of the minimum angle of resolution (logMAR) (Snellen equivalent, 20/25) in the L-DALK group vs 0.22±0.10 logMAR (Snellen equivalent, 20/32) in the S-DALK group. Differences were observed between the L-DALK group and the S-DALK group in terms of refractive sphere (p=0.015), manifest cylinder (p=0.014) and spherical equivalent refractive error (p=0.034) at any time interval postoperatively. At 24 months, the mean spherical equivalent refractive error was -3.5±3.2 D and -5.2±2.6 D in the L-DALK and S-DALK groups, respectively.


CONCLUSIONS
L-DALK can reduce the degree of postoperative myopia and manifest astigmatism and improve visual acuity outcomes in keratoconus compared with S-DALK.


BACKGROUND
Chinese Clinical Trial Registry (TRC-13003122).
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Ting
T
Huang
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Yunwei
Y
Hu
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Mengru
M
Gui
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Hong
H
Zhang
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Yun
Y
Wang
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Chao
C
Hou
D000328:Adult; D000704:Analysis of Variance; D016039:Corneal Transplantation / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D012030:Refractive Errors / Q000503:physiopathology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
Clinical Trial; Cornea; Treatment Surgery