Purpose: To analyze the visual outcomes and method of final visual correction in eyes with corneal ectasia after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK).
Setting: Emory University Department of Ophthalmology and Emory Vision, Atlanta Georgia, USA.
Methods: This retrospective review comprised 74 eyes of 45 patients with corneal ectasia after LASIK (72 eyes) or PRK (2 eyes). Outcomes included postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), best corrected visual acuity (BCVA), and refraction; method of final visual correction; and time to rigid gas-permeable (RGP) contact lens failure.
Results: Corneal ectasia developed a mean of 19.2 months after surgery. Postoperatively, the mean UCVA was 20/400, the mean BSCVA before ectasia management was 20/108, and the mean BCVA was 20/37. After ectasia management, the final BCVA was 20/40 or better in 78% of eyes. Final visual correction was achieved with RGP lenses in 77% of eyes, spectacles in 9%, collagen crosslinking in 3%, intracorneal ring segments in 1%, and penetrating keratoplasty (PKP) in 8%. Two eyes with intracorneal ring segments required segment explantation and subsequent PKP. One eye that had PKP had a graft-rejection episode; there were no graft failures. Two eyes (3%) did not require a visual device to improve visual acuity. The mean time to successful RGP lens wear was 24.8 months; 80% of cases initially managed with RGP lenses were successful with this form of treatment.
Conclusions: The majority of eyes developing postoperative corneal ectasia achieved functional visual acuity with RGP lens wear and did not require further intervention. Penetrating keratoplasty can usually be postponed or avoided by alternative methods of visual rehabilitation; however, PKP, when necessary, can provide good visual outcomes.
Purpose: To analyze the changes in higher-order aberrations (HOAs) that occur after wavefront-optimized photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).
Setting: Private practice, Atlanta, Georgia, USA.
Methods: This retrospective analysis comprised eyes that had PRK or LASIK from June 2004 through October 2005. Postoperative outcome measures included 3-month uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction spherical equivalent (MRSE), changes in the root mean square (RMS) and grouped coefficient HOAs (microns) measured with a corneal analyzer, and subjective assessment of visual aberrations.
Results: One hundred consecutive eyes of 54 patients had PRK, and 100 contemporaneous consecutive eyes of 71 patients had LASIK. The PRK and LASIK populations were similar in general demographics, preoperative HOAs, and postoperative UCVA and BSCVA. The mean MRSE was slightly hyperopic after PRK (mean +0.11 diopters [D]) and slightly myopic after LASIK (mean −0.19 D) (P<.0001). There were no statistically significant changes in RMS or grouped coefficient HOA values after PRK or LASIK, nor were there significant differences in postoperative RMS or grouped coefficient HOA values between PRK and LASIK. One percent of PRK and LASIK patients reported a subjective increase in postoperative visual aberrations; 5% reported a subjective improvement postoperatively.
Conclusions: Wavefront-optimized excimer laser surgery did not induce significant HOAs after PRK or LASIK. The 2 techniques were equally efficacious and had equivalent postoperative HOA profiles.
Purpose: To determine the effect of different blades on laser in situ keratomileusis (LASIK) flap thickness created with the Amadeus I microkeratome (Ziemer Ophthalmic Systems).
Setting: Emory University Department of Opthalmology and Emory Vision, Atlanta, Georgia, USA.
Methods: This retrospective nonrandomized comparative case study from January 2005 through June 2006 compared LASIK flap thickness created with blades from 2 manufacturers: the Surepass from Surgical Instrument Systems and distributed by AMO and the ML7090 CLB distributed by Med-Logics, Inc. Sex, preoperative corneal thickness, surgical-eye sequence, flap thickness and variance, and residual stromal bed were evaluated in each group.
Results: This study evaluated 424 eyes of 226 patients. Surepass blades were used in 238 eyes and ML7090 CLB blades in 186 eyes. There were no significant differences between the 2 blade groups in preoperative corneal thickness, sex, or cases with corneal thickness greater than 550 µm. Mean flap thickness and variance were significantly lower in the ML7090 CLB group than in the Surepass group (P<.0001). There were no significant differences in flap thickness in either group based on sex; however, in both groups, flap thickness was significantly lower in second eyes and in eyes with a preoperative thickness less than 550 µm (P<.001).
Conclusions: The Amadeus I microkeratome created thinner, more consistent LASIK flaps with the ML7090 CLB blade than with the Surepass blade. Preoperative corneal thickness and eye sequence affected flap thickness, while sex did not.
A 47-year-old woman required penetrating keratoplasty in the right eye after developing delayed visually significant corneal scarring bilaterally after laser in situ keratomileusis (LASIK) in 1997 following epikeratoplasty in 1987. Spectral domain ocular coherence tomography of the left cornea showed a 100 μm lenticule with a LASIK flap posterior to the host Bowman layer at 250 μm. Histopathology and electron microscopy of the right corneal button showed a 120 μm lenticule with a LASIK flap within the lenticule at 100 μm. Clinically significant scarring was present within the LASIK flap interface, within the lenticule stroma, and within the area of the underlying host Bowman layer. There were keratocytes at the junction between the LASIK flap and lenticule stromal bed. Although epikeratoplasty is no longer practiced, post-epikeratoplasty patients may present for refractive surgical options and LASIK carries significant risks for corneal scarring in these individuals, especially when using flap-creating devices that may create thin LASIK flaps.
Purpose: To measure central flap thickness in eyes with ectasia after laser in situ keratomileusis (LASIK) and to compare these values with estimated anticipated flap thickness based on mean published values for each device used for flap creation. Setting: Emory Vision at Emory University, Atlanta, Georgia, USA.
Design: Retrospective comparative case series, using published data for controls.
Methods: Confocal microscopic analysis was performed using the Confoscan 3 device to measure central flap thickness in eyes with ectasia after LASIK. Pre-LASIK records were evaluated for information, including basic patient demographics, preoperative corneal topographies, estimated anticipated flap thickness based on the mean average thickness values, and residual stromal bed (RSB) thickness calculations using measured and estimated flap thicknesses.
Results: Fifty eyes of 29 patients were evaluated. The mean measured flap thickness was 138 μm ± 26 (SD) (range 90 to 220 μm). There were no significant differences between measured and estimated flap thicknesses (138 μm versus 135 μm; P=.5) or RSB thickness (329 μm versus 332 μm; P=.7), nor were there differences in flap thickness between eyes developing ectasia with normal corneal topographies and eyes with abnormal corneal topographies. One eye had a measured flap resulting in an unintended RSB thickness less than 250 μm; this eye also had abnormal topography.
Conclusions: Measured central flap thickness was not thicker than estimated in most eyes developing ectasia after LASIK. Thus, excessively thick flaps do not appear to be a major contributing factor to the pathogenesis of ectasia after LASIK
A 43-question survey was e-mailed to all resident members of the American Society of Cataract and Refractive Surgery (ASCRS), ASCRS members in practice for 5 or fewer years, and residency program directors of 118 U.S. Accreditation Council for Graduate Medical Education-accredited ophthalmology programs (for distribution to their residents) in June 2010. Two hundred eighty-five of 2279 surveys sent were completed and returned, for a response rate of 12.5%. Most respondents (88.7%) had served as primary surgeon in more than 100 cataract surgeries. Fifty-two percent of respondents had not performed corneal relaxing incisions; 60% had no experience implanting a toric IOL. Twenty-two percent had experience implanting a presbyopia-correcting IOL. Over 75% had not performed any corneal refractive surgical procedures. Although basic cataract case numbers appear adequate, there are significant perceived deficiencies in current resident training models for surgical astigmatism management, implanting presbyopia-correcting IOLs, and corneal refractive surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
Purpose: To determine whether measurements obtained by partial coherence interferometry (PCI) correlate well with measurements obtained using immersion ultrasound (US) in children.
Setting: Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, USA.
Design: Evaluation of a diagnostic test or technology.
Methods: The charts of pediatric patients who had cataract surgery from August 2008 to September 2009 were reviewed. Axial length (AL) measurements in the operative eye were obtained using PCI at the preoperative clinic visit and then using immersion US in the operating room before surgery. The data were compared to determine the degree of agreement.
Results: The charts of 18 patients (27 eyes) were reviewed. Preoperative AL measurements by PCI were obtained in 21 eyes (78%). On average, the PCI-measured ALs were 0.1 mm less than the immersion US values (95% confidence interval, −0.2 to −0.1; P = .002). All eyes with an AL of 23.5 mm or less had lower PCI values than immersion US values. There was no systematic pattern of 1 measurement being greater or less than the other in eyes with an AL longer than 23.5 mm.
Conclusions: There is a systematic difference in AL measurement between PCI and immersion US, with PCI tending to give lower values, particularly in eyes with an AL longer than 23.5 mm. Depending on the length of the eye, a 0.1 mm error in AL measurement could result in a 0.25 to 0.75 diopter difference in intraocular lens calculation that could be clinically significant in some patients.
Purpose: To study the effect of flap thickness on visual acuity and refractive outcomes after laser in situ keratomileusis (LASIK) using 2 blade types with a mechanical microkeratome.
Setting: Emory Vision, Atlanta, Georgia, USA.
Methods: This retrospective analysis was of LASIK cases performed between January 2005 and June 2006 using an Amadeus I microkeratome and an ML7090 CLB blade (blade A) or a Surepass blade (blade B). Outcomes analyzed included flap thickness, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), the enhancement rate, and surgical complications 3 months postoperatively.
Results: Two hundred sixty-three eyes of 153 patients were analyzed; blade A was used in 158 eyes and blade B, in 105 eyes. The mean flap thickness was significantly thinner with blade A than with blade B (107 μm ± 12 [SD] versus 130 ± 20 μm) (P<.0001). There was no overall correlation with either blade between flap thickness and UDVA, CDVA, or MRSE (all r<0.2). At 3 months, there was no statistically significant difference in UDVA, CDVA, or MRSE between the 2 blade groups at 3 months (all P > .10), and there was no difference in the complication rates.
Conclusion: Flap thickness did not affect visual or refractive outcomes with a mechanical micro-keratome with either blade type.
Financial Disclaimer: No author has a financial or proprietary interest in any material or method mentioned.
A 40 year-old Caucasian male, status post radial keratotomy OU in 1993, suffered pain, extreme photophobia, and mild loss of uncorrected visual acuity in the right eye after being struck by a nail. The patient presented with a small deep stromal lesion and was initially treated with a variety of antibiotic regimens without improvement in the lesion’s appearance. Upon referral the patient had confocal microscopy performed, which clearly demonstrated epithelial cells in the deep stroma and on the endothelial surface. Upon cessation of all medications the patient’s mild symptoms resolved, and his clinical appearance has remained stable without intervention for 9 months. Patients with radial keratotomy incisions are at risk for traumatic epithelial downgrowth even many years after surgery. Confocal microscopy can make the definitive diagnosis of epithelial downgrowth. Management of this condition remains controversial.