Nasal Hinge Flap Research Articles

Inadequate Results for Microkeratome-assisted Additive Stromal Keratoplasty for Management of Keratoconus

To evaluate a new automated technique--microkeratome-assisted additive stromal keratoplasty (MASK)--for the management of keratoconus in eyes scheduled for surgery with clear cornea associated with total contact lens intolerance. This non-comparative, interventional case series included four eyes of four patients with stage I and II keratoconus associated with total contact lens intolerance. The first step of the surgical procedure consisted of performing a nasal-hinged flap on the host cornea with a microkeratome. The second step consisted of extracting a stromal piano-powered disk from the donor's cornea using an artificial chamber. The 80-microm thick lamellar graft was punched with a 7.5-mm circular trephine and positioned beneath the flap. Corneal refractive surgery was scheduled for the end of the sixth postoperative month. No corneal refractive surgery was performed after 6 months of follow-up. Only one eye gained five lines of best spectacle-corrected visual acuity (BSCVA). Among the other three eyes, two had unchanged BSCVA and one lost one line of BSCVA. At the end of surgery, mean corneal thickness was increased by 148.75 microm. Microkeratome-assisted additive stromal keratoplasty appears to be a safe and straightforward surgical technique that preserves the host endothelium and avoids the need of an open-sky procedure. However, in our study, MASK is not considered as an alternative to penetrating or deep lamellar keratoplasty in the management of keratoconus with clear cornea because of imprecise anatomic and refractive outcomes.

The Incidence and Risk Factors for Developing Dry Eye After Myopic LASIK

To determine the incidence of dry eye and its risk factors after myopic laser-assisted in situ keratomileusis (LASIK). Single-center, prospective randomized clinical trial of 35 adult patients, aged 24 to 54 years, with myopia undergoing LASIK. setting and study population: Participants were randomized to undergo LASIK with a superior or a nasal hinge flap. They were evaluated at 1 week and 1, 3, and 6 months after surgery. intervention: Bilateral LASIK with either a superior-hinge Hansatome microkeratome (n = 17) or a nasal-hinge Amadeus microkeratome (n = 18). main outcome measures: The criterion for dry eye was a total corneal fluorescein staining score > or =3. Visual acuity, ocular surface parameters, and corneal sensitivity were also analyzed. Cox proportional-hazard regression was used to assess rate ratios (RRs) with 95% confidence intervals. The incidence of dry eye in the nasal- and superior-hinge group was eight (47.06%) of 17 and nine (52.94%) of 17 at 1 week, seven (38.89%) of 18 and seven (41.18%) of 17 at 1 month, four (25%) of 16 and three (17.65%) of 17 at 3 months, and two (12.50%) of 16 and six (35.29%) of 17 at 6 months, respectively. Dry eye was associated with level of preoperative myopia (RR 0.88/each diopter, P = .04), laser-calculated ablation depth (RR 1.01/microm, P = 0.01), and combined ablation depth and flap thickness (RR 1.01/microm, P = 0.01). Dry eye occurs commonly after LASIK surgery in patients with no history of dry eye. The risk of developing dry eye is correlated with the degree of preoperative myopia and the depth of laser treatment.

Hyperopic Laser in situ Keratomileusis With 5.5-, 6.5-, and 7.0-mm Optical Zones

To evaluate the results of laser in situ keratomileusis (LASIK) for the correction of hyperopia and hyperopic astigmatism using a large 7.0-mm optical zone and to compare them with treatments using a 5.5- and 6.5-mm optical zone. One hundred sixty-one eyes of 89 patients with a mean preoperative spherical equivalent refraction of +2.44 +/- 1.32 diopters (D) (range: +0.00 to +5.62 D, cylinder 5.25 to 0.00 D) were treated for hyperopia and hyperopic astigmatism using a 7.0-mm optical zone and were analyzed retrospectively. Postoperatively, patients were examined after 1 day, 1 week, 1 month, 3 months, and 1 year. Eyes treated previously at the same center by the same surgeons with 5.5- and 6.5-mm optical zone applications were used as controls. All treatments were performed with the Nidek EC 5000 CXII excimer laser system (Nidek, Gamagori, Japan). A nasal hinged flap was created using the Nidek MK 2000 microkeratome in all cases. The mean postoperative spherical equivalent refraction after 1 month (n=89) was +0.12 +/- 0.72 D (range: -1.75 to +2.75 D), +0.13 +/- 0.74 D (range: -1.88 to +1.62 D) at 3 months (n=70), and +0.20 +/- 0.69 D (range: -1.62 to +1.12 D) at 1 year (n=33). Regression between 1 month and 1 year was 0.08 D in the 7.0-mm optical zone group. Regression was 0.25 D in the 5.5-mm group and 0.02 D in the 6.5-mm optical zone group between 1 month and 1 year. In both the 5.5- and 6.5-mm optical zone groups, 13% of eyes lost one line in visual acuity (2% in the 7.0-mm optical zone group). The gain of one or more lines in visual acuity was 19% in the 5.5-mm group, 17% in the 6.5-mm group, and 27% in the 7.0-mm optical zone group. All data represent primary cases without retreatment. Increasing the optical zone size from 5.5 mm to 6.5 mm and to 7.0 mm seems to improve refractive results, stability, and safety of hyperopic and hyperopic-astigmatic LASIK treatments. Although some hyperopic and astigmatic eyes are endangered by loss of lines in best spectacle-corrected visual acuity, more eyes gain one or more lines.

The effect of corneal flap on optical aberrations

Purpose To evaluate the changes in ocular aberrations induced by corneal flap creation. Design Prospective interventional nonrandomized clinical trial. Methods This study included 15 patients who were scheduled for laser in situ keratomileusis. A nasal hinge flap was created, using the Nidek MK-2000 microkeratome and then replaced without performing laser ablation. The ocular aberrations were measured before and after flap creation using the Nidek Optical Path Difference Scanning System ARK-10000. Results The root mean square wavefront errors of the higher-order optical aberrations (third-, fourth-, fifth-, and sixth-order aberrations) were not significantly altered at 1 week postsurgery compared with the preoperative values ( P > .35). Conclusions Creating a corneal flap with the Nidek MK-2000 microkeratome did not induce changes in higher-order optical aberrations as measured with the Nidek Optical Path Difference Scanning System ARK-10000 during the early postoperative period.

Effect of flap hinge placement on post-laser in situ keratomileusis wound healing in the presence of superior corneal vascularization

We report a case that demonstrates a difference in wound healing after laser in situ keratomileusis using microkeratomes with both superior and nasal hinges in a patient with bilateral superior corneal vascularization. Subsequently, the patient experienced lamellar keratitis, epithelial defects, and peripheral thinning in both eyes. These postoperative conditions were more extensive and required more time to resolve in the eye with a nasal hinge flap. Creating a superiorly hinged flap decreases the likelihood of transecting extensive corneal pannus and may reduce the degree of postoperative complications.

The effect of hinge position on corneal sensation and dry eye after LASIK

Purpose To investigate the effect of hinge position on corneal sensation and dry eye syndrome after laser in situ keratomileusis (LASIK). Design Prospective, randomized, self-controlled trial. Participants Fifty-two patients ≥18 years of age undergoing bilateral LASIK. Intervention Patients underwent bilateral LASIK with the superior-hinge Hansatome microkeratome in one eye and the nasal-hinge Amadeus microkeratome in the other eye. In all eyes, the flaps were 160 μm thick, with a diameter of 9.5 mm. Main outcome measures Masked Cochet–Bonnet esthesiometry was performed centrally before surgery and at 1 week, 1 month, 3 months, and 6 months after surgery. Dry eye was evaluated at the same time intervals with lissamine green corneal and conjunctival staining, Schirmer testing with anesthesia, and tear-film breakup time. Subjective evaluation of dry eye sensation was performed at 3 and 6 months after surgery. Results Corneal sensation was reduced in eyes with either superior- or nasal-hinge corneal flaps at 1 week, 1 month, and 3 months after surgery ( P < 0.001). Compared with preoperative values, a significant reduction in corneal sensation remained at 6 months in corneas with superior-hinge flaps ( P < 0.001) but not in corneas with nasal-hinge flaps ( P = 0.263). Mean corneal sensation was greater in corneas with a nasal-hinge flap compared with corneas with a superior-hinge flap at all postoperative visits ( P < 0.001). The loss of sensation was greatest at 1 week and showed improvement at each subsequent time interval up to 6 months. Overall, dry eye signs and symptoms were greatest during the immediate postoperative period and improved at all subsequent time intervals. Dry eye signs and symptoms were generally greatest in the eyes with a superior-hinge flap and milder in eyes with a nasal-hinge flap. Conclusions The long posterior corneal nerves, which innervate the cornea, enter the eye at 3- and 9-o’clock. A superior-hinge flap transects both arms of the neuroplexus, whereas a nasal hinge transects only the temporal arm. LASIK results in a significant reduction in corneal sensation. Corneal sensation and dry eye signs and symptoms decreased immediately after LASIK and improved at all time periods between 1 week and 6 months in eyes with both a nasal-hinge flap and a superior-hinge flap. However, the loss of corneal sensation and presence of dry eye syndrome were greater in eyes with a superior-hinge flap than in eyes with a nasal-hinge flap.

Laser in situ keratomileusis results after intrastromal corneal ring segments (Intacs)

Objective To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) after removal of intrastromal corneal ring segments (Intacs, KeraVision, Fremont, CA) from the cornea. Design Single-center, noncomparative, interventional, consecutive case series. Participants Nine eyes of nine consecutive patients who had undergone LASIK after Intacs of experimental design removal were analyzed for this study. Intervention A standard LASIK procedure was performed with the Nidek EC 5000 excimer laser (Nidek, Gamagori, Japan) at intervals between 4 and 10 months after Intacs explantation. A Nidek MK 2000 microkeratome (Nidek, Gamagori, Japan) or a Chiron Automated Corneal Shaper (Bausch & Lomb, Claremont, CA) with a 130- to 180-μm thickness plate was used to create a nasal hinged flap in a plane superficial to the previous Intacs channel. Main outcome measures Uncorrected visual acuity, manifest refraction, best spectacle-corrected visual acuity, and topography were measured preoperatively and at months 1, 3, 6, and 12 after LASIK. Results Faint residual scarring in the channels after Intacs removal was seen in all patients. No difficulties were encountered during the ablation or flap replacement. Eight of nine patients had 20/20 or better uncorrected visual acuity after a single LASIK procedure. Mean spherical equivalent at 12 months was −0.6, ranging from −1.25 to +0.25 diopter. One patient had glare develop secondary to superior corneal thinning and scarring after implantation of a nonstandard Intacs. No patient lost lines of best spectacle-corrected vision after LASIK. Conclusion Reversibility of the myopic Intacs is demonstrated. Removal of Intacs may be followed by a safe and effective LASIK for low to moderate myopia.

Epithelial Folds Following Slippage of LASIK Flap

We present a case of a slipped corneal flap after laser-assisted in-situ keratomileusis, LASIK. A 22-year-old, female with myopia and a refractive error of -5.50 D sph OU had an uneventful LASIK performed on her left eye with a Chiron Automated Corneal Shaper (ACS) and a VISX-Star Excimer laser using a nasal hinged flap. On the first postoperative day, slit lamp examination revealed 4.0 mm slippage of the corneal flap. The flap was rolled and folded on itself within the inferior cul-de-sac. With the aid of the operating microscope, the flap was repositioned on the stromal bed. Immediately following the repositioning, many folds were still visible despite centering the flap on the stromal bed and performing stretching maneuvers. Detailed examination showed the folds to be of edematous epithelial origin. The underlying stromal bed was flat. Within days following repositioning, the folds had disappeared and the flap assumed the typical postoperative LASIK appearance. The final uncorrected visual acuity returned to 20/20.

Effectiveness of LASIK to Correct Refractive Error After Penetrating Keratoplasty

Refractive errors may invalidate the good results of penetrating keratoplasty (PK). The Authors evaluate the effectiveness of excimer laser in situ keratomileusis (LASIK) in the correction of refractive error after PK. Four patients, a 26-year-old woman, a 54-year-old man, a 19-year-old man, and a 51-year-old woman, showed refractive errors: -11 = -4.5 x 85 ; -8, -4.5 = -11 x 95 ; and -4.5 = -4 x = 1200, with a clear graft at least 20 months after penetrating keratoplasty secondary to keratoconus. However, they underwent the LASIK procedure with a nasal-hinged flap of 160 um. No sutures were placed. At follow-up, 24, 18, 12, and 12 months, respectively, the graft remained clear and the endothelial cells were unchanged. The uncorrected visual acuities were 20/50, 20/25, 20/50, and 20/25, respectively with an unchanged best corrected visual acuity (20/20) for all patients. No significant complications were observed. LASIK procedure seems to be an effective technique to correct refractive error after successful penetrating keratoplasty.

Videokeratographic changes after laser in situ keratomileusis to correct high myopia

Purpose To evaluate the videokeratographic changes and patterns after laser in situ keratomileusis (LASIK) in high myopia using computerized videokeratography. Setting San Salvatore Hospital, Chair of Ophthalmology, University of L’Aquila, L’Aquila, Italy. Methods Forty-one eyes of 26 patients treated with no-suture nasal-hinged flap LASIK for an attempted mean spherical equivalent correction of −13.9 diopters (D) ± 4.1 (SD) (range −8.0 to −22.0 D) were evaluated. Mean patient age was 35.2 ± 9.8 years. Mean follow-up was 15.1 ± 6.7 months (range 6 to 26 months). Results Thirty-five eyes (85.4%) were within ±2.0 D of the planned correction, with a refractive error greater than 3.0 D in the 7.3% of eyes. Mean central corneal power decreased from 43.2 ± 1.8 D (range 38.70 to 47.40 D) to 35.8 ± 3.8 D (range 30.3 to 42.6 D). Mean preoperative corneal astigmatism decreased from 1.2 ± 0.9 D (range 0.2 to 4.2 D) to 0.9 ± 0.9 D (range 0.2 to 3.3 D). Videokeratographic qualitative analysis showed corneal shape changes within 15 days after surgery. Corneal patterns then stabilized, and 37 eyes (90.3%) had no significant modifications in corneal refractive power after 1 month. Conclusion After LASIK in highly myopic eyes, videokeratographic maps showed corneal power stabilized within 1 month in most eyes and there was no irregular astigmatism if the treatment was well centered.

Laser in situ keratomileus using the LaserSight 200 laser: results of 950 consecutive cases

Purpose To examine the refractive outcome in 950 consecutive eyes having laser in situ keratomileusis (LASIK) by 1 surgeon with experience in keratomileusis. Setting Outpatient excimer laser surgical facility. Methods This study comprised 950 consecutive eyes of 475 patients having LASIK as a primary procedure with a LaserSight 200 excimer laser (8.51 software). A nasal hinged flap and a Chiron microkeratome were used. Preoperative cycloplegic refraction was done only in patients younger than 25 years and in all hyperopic cases. Subjective preoperative and postoperative manifest refractions were done after autorefractometry in all cases. In cases of hyperopia, the software was modified by adding 30% to the refractive error. Enhancement results are not included. Results Of the 950 eyes, 893 (94.00%) were myopic and 57 (6.00%), hyperopic. In the low myopia group (1.00 to 3.99 D) of 223 eyes (24.97%), mean spherical equivalents (SEs) were −2.90 D ± 0.56 (SD) preoperatively, −0.46 ± 0.6 D 3 months postoperatively, and −0.41 ± 0.5 D 6 months postoperatively. In the moderate myopia group (4.00 to 5.99 D) of 205 eyes (22.96%), respective mean SEs were −4.90 ± 0.7 D, −0.90 D ± 0.9 D, and −0.67 ± 0.7 D. In the high myopia group (6.00 to 9.99) of 266 eyes (25.30%), the respective means were −7.70 ± 1.3 D, −0.76 ± 0.99 D, and −0.60 ± 0.8 D. In the extreme myopia group (10.21 to 30.00) of 199 eyes (22.28%), the respective means were −13.30 ± 2.9 D, −1.30 ± 1.4 D, and −1.13 ± 1.3 D. For the entire myopic group, the mean astigmatism was +1.55 ±1.38 D, +1.09 ± 0.92 D, and +0.87 ± 0.77 D, respectively. The low hyperopia group (1.00 to 2.99 D) of 39 eyes (68.42%) had a mean preoperative SE of +1.80 ± 0.59 D and mean postoperativeSEs of +1.00 ± 0.76 D at 3 months and +1.16 ± 0.52 D at 6 months. The respective means in the moderate hyperopia group (3.00 to 6.00) of 18 eyes (31.57%) were +4.62 ± 1.19 D, +3.71 ± 1.12 D, and +4.00 ± 1.07 D. Conclusions Laser in situ keratomileus for myopia using the LaserSight 200 excimer laser was stable with time and safe for the correction of different degrees of myopia. In the hyperopic group, marked regression occurred in a large percentage of patients. Thus, we will not perform LASIK for hyperopia until the software improves.