A femtosecond laser-generated, zigzag-shaped incisions result in a more rapid recovery of best spectacle-corrected visual acuity and induce less astigmatism compared with conventional blade trephination penetrating keratoplasty, says research from the University of California, Irvine. Authors evaluated the procedures through a retrospective comparison of a consecutive surgical series involving 57 consecutive patients who underwent PKP at the university. They compared 49 eyes of 43 patients who underwent femtosecond laser zigzag incision pattern PKP with 17 eyes of 14 patients who underwent conventional Barron suction trephination PKP performed contemporaneously. All PKPs were closed with an identical, 24-bite running nylon suture technique. The main outcome was determined by measuring topographically determined astigmatism, BSCVA and recovery of full visual potential.
The postoperative follow-up ranged from one to 12 months. There was a significant difference in average astigmatism between the groups at postoperative month one (p=0.013) and three (p=0.018). By month three, the average astigmatism was 3 D in the zigzag group and 4.46 D in the conventional group. Of the patients with normal macular and optic nerve function (nzz=32; ncon=14), a significant difference in BSCVA was seen at month one (p=0.0003) and month three (p=0.006) with 81 percent of the zigzag group versus 45 percent of the conventional group achieving BSCVA of ≥20/40 by month three (p=0.03).
(Ophthalmology 2009;116:1638-43)
Farid M, Steinert RF, Gaster RN, et al.
Different Inclusion Criteria May Change CXL
A recent study performed in Zurich has shown that changing the inclusion criteria may significantly reduce the complications and failures of corneal crosslinking. In this prospective study, eyes with verified, progressive, primary keratectasia had standard crosslinking. Preoperative and six- and 12-month postoperative examinations included corrected distance visual acuity, slit-lamp evaluation, applanation tonometry and Scheimpflug imaging. Statistical analysis included analysis of variance and the Mann-Whitney U test to detect risk factors for complications.
The authors evaluated 117 eyes of 99 patients with approximately 90 percent completing the 12-month follow-up. The complication rate (percentage of eyes losing two or more Snellen lines) was 2.9 percent (95 percent confidence interval, 0.6 percent to 8.5 percent).
The failure rate of corneal crosslinking (percentage of eyes with continued progression) amounted to 7.6 percent. Eyes older than 35 years with a preoperative CDVA better than 20/25 were classified as being at significant risk of complications. A high preoperative maximum keratometry reading proved to be a significant risk factor for failure as well.
Sterile infiltrates were seen in 7.6 percent of eyes, and central stromal scars in 2.8 percent.
The results of the study also showed that a preoperative maximum keratometry reading less than 58 D may reduce the failure rate to less than 3 percent, and restricting patient age to younger than 35 years may reduce the complication rate to 1 percent.
(J Cataract Refract Surg 2009;35:1358-62)
Koller T, Mrochen M, Seiler T.
LAL Shines a Light on Myopia
Light-adjustable lens technology has been shown to correct residual myopia errors up to -1.5 D and significantly improve uncorrected visual acuity without compromising best-corrected visual acuity, according to a new study. The authors conducted the prospective clinical study on 14 eyes of 14 patients at Codet Vision Institute in
-1.5 D. They were then treated with a spatial intensity profile delivered by a digital light delivery device to induce a targeted myopic refractive change. Once the desired myopic correction was achieved, the LAL was treated again to lock in the lens power. The manifest refraction—UCVA and best- or spectacle-corrected visual acuity—were measured with a follow-up time of one to nine months to determine the achieved refractive corrections and their stability.
Of 14 eyes, 13 (92.9 percent) were within 0.25 D of the target refraction at one day post lock-in, with 100 percent of the eyes achieving the targeted refractive adjustment within 0.5 D or better with up to nine months postoperative follow-up. All eyes treated showed no change in manifest spherical refraction >0.25 D between one day post lock-in, and the three, six and nine months postoperative visits. The data demonstrate the stability of the achieved refractive change after the adjustment and lock-in procedures. The mean rate of change was 0.006 D per month, which is six times more stable than that of laser corneal refractive procedures.
(Ophthalmology 2009;116:1432-5)
Chayet A, Sandstedt C, Chang S, et al.
PKP Rejection Medication Candidates Reduced to a Short List
A recent evaluation of the range of medications surgeons use to prevent routine rejection after PKP provides a baseline for prospective studies of medications and dosing to prevent these rejections.
Between March 2006 and June 2008, corneal surgeons taking an endothelial keratoplasty course at Price Vision Group, a tertiary referral center in
While the range of topical steroid dosing after initial PKP was wide, the narrow interquartile range did reflect commonly held opinions.
(Cornea 2009;28:865-70)
Price FW Jr, Price DA, Ngakeng V, et al.
FD-OCT
Fourier-domain optical coherence tomography has been shown to be superior to time-domain optical coherence tomography for the detection of many clinically relevant features of vitreoretinal disease, according to new research. A prospective, observational study was conducted to test the two methods. FD-OCT scans (128 B-scans x 512 A-scans) were obtained using a prototype instrument (3D-OCT; Topcon) in 50 eyes of 28 consecutive patients undergoing conventional high-resolution (6 B-scans x 512 A-scans) TD-OCT imaging (Stratus OCT; Carl Zeiss Meditec). Each image set was reviewed independently for the presence of clinical findings of interest, and device sensitivities were calculated.
The results showed that the average sensitivity for detection of all features was 94 percent for FD-OCT and 60 percent for TD-OCT. Clinical findings were identical between devices in 18 percent (9/50) of cases. FD-OCT detected features that were not visible on conventional OCT scans in 78 percent (39/50) of cases. FD-OCT was more sensitive than TD-OCT for the detection of multiple findings, including diffuse intraretinal edema (87 percent vs. 60.9 percent), subretinal fluid (100 percent vs. 46.2 percent), large pigment epithelium detachments (100 percent vs. 81 percent) and subretinal tissue (100 percent vs. 61.5 percent).
The greater sensitivity of FD-OCT systems for the detection of intraretinal and subretinal fluid may be of particular importance for the treatment of patients with neovascular age-related macular edema. FD-OCT is likely to supplant TD-OCT as the gold standard of care for retinal specialists in the near future, say the authors.
(Am J Ophthalmol 2009;148:242-248. Epub 2009 May 9)
Keane PA, Bhatti RA, Brubaker JW, et al.
New Factors Found for Successfully Predicting Ocular Melanoma
A recent study has helped to establish several factors that can predict the growth of choroidal nevi into melanoma. The factors discovered included greater tumor thickness, subretinal fluid, symptoms (flashing and floaters), orange pigment, tumor margin near the optic disc, and two otherwise new features: ultrasonographic hollowness and absence of halo.
The study, a retrospective medical record review, evaluated 2,514 eyes. Kaplan-Meier estimates and Cox regression analyses were used. The median tumor basal diameter was
5 mm and thickness was 1.5 mm. Nevus growth into melanoma occurred in 2 percent, 9 percent and 13 percent of eyes at one, five and 10 years, respectively. Factors predictive of growth into melanoma by multivariable analysis included tumor thickness greater than 2 mm (p<0.001), subretinal fluid (p=0.002), symptoms (p=0.002), orange pigment (p<0.001), tumor margin within 3 mm of the optic disc (p=0.001), ultrasonographic hollowness (p<.001) and halo absence (p=0.009).
In order to recall these risk factors for ocular melanoma, the authors of the study suggested the following mnemonic device: "To Find Small Ocular Melanoma Using Helpful Hints," representing Thickness, Fluid, Symptoms,
(Arch Ophthalmol 2009;127:981-7)
Shields CL, Furuta M, Berman EL, et al.
Intacs with CXL Proves Effective Against Keratoconus
Transepithelial cross-linking in addition to Intacs implants (Addition Technologies) has been proven an effective treatment for keratoconus, according to a recent study. The authors of the study evaluated 25 eyes of 17 patients with bilateral keratoconus who underwent Intacs implantation with subsequent CXL treatment. Inclusion criteria included absence of corneal scarring, contact lens intolerance, corneal thickness greater than 400 µm and endothelial cell density greater than 3,000/mm2. Preoperative and three-month postoperative uncorrected visual acuity, best-corrected visual acuity, manifest refractions and measures of the mean and steepest keratometric values were reviewed retrospectively. The results in the Intacs group were compared
with those obtained after CXL/Intacs.
The study included 10 males and five females; the mean age was 25.14 ±7.11 (range 16 to 39) years old. Mean time between implantation of Intacs and CXL was 3.98 months. CXL after Intacs resulted in an additional improvement in UCVA, BCVA, sphere, cylinder and keratometry. Intacs resulted in an improvement of 1.9 Snellen lines (p<0.05) of UCVA and 1.7 Snellen lines (p<0.05) of BCVA. CXL performed after Intacs treatment yielded an additional 1.2 Snellen lines (p<0.05) of UCVA and 0.36 Snellen lines (p<0.05) of BCVA.
The decrease in spherical, cylindrical, mean and steepest keratometric values was 2.08 D (p<0.05), 0.47 D (p>0.05), 2.22 D (p<0.05) and 1.27 D (p<0.05), respectively, after Intacs treatment. An additional 0.5 D (p<0.05), 0.15 D (p>0.05), 0.35 D (p>0.05) and 0.76 D
(p<0.05) of improvement was gained after CXL in each respective parameter.
(Cornea 2009;28:719-23)
Ertan A, Karacal H, Kamburoğlu G.
Lipid Layer Thickness Shown to be Closely Related to Dry Eye
Data from a recent, two-pronged study has not only demonstrated that there a strong correlation between the occurrence of dry eye and lipid layer thickness, but it also revealed that interferometry has a practical usage in clinical practice. The authors of the study recruited patients presenting consecutively for routine eye examinations (n=137; age range=18 to 60 years; mean=41.7 ±15.5 years; 102 females and 35 males). Patients were required to complete the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire after which their LLT was evaluated using a new interferometer (Ocular Surface Interferometer). Patients were assigned to one of three symptom categories: no symptoms (SPEED=0); mild to moderate symptoms (SPEED=1 to 9) and severe symptoms (SPEED≥10). Categorical analysis (contingency table) and linear regression were also performed on the data.
Results showed that for patients with severe dry-eye symptoms, 74 percent had an LLT ≤60 nm. Conversely, 72 percent of patients with no dry-eye symptoms had an LLT of ≥75 nm (contingency table, x2=12.63, df=2, p=0.0018). Furthermore, a linear regression of LLT and SPEED score revealed a significant linear relationship (as LLT increases, SPEED score decreases; p=0.0014).
(Cornea 2009;28:789-94)
