Corneal surface topography and associated visual performance with INTACS for myopia: phase III clinical trial results. The INTACS Study Group

Late extrusion of intrastromal corneal ring segments: A report of two cases

Purpose

To report two cases of patients with late extrusion following uneventful implantation of intrastromal corneal ring segments (ICRS) for myopia.

Observations

Two patients with previously implanted ICRS for low myopia presented with spontaneous onset of extrusion of their ICRS, one at 7 years post-operatively and the other at 17 and 20 years. Both cases underwent explantation and maintained excellent best-corrected visual acuity. These cases represent the longest reported intervals between implantation of the ICRS and subsequent extrusion.

Conclusions and importance

Late extrusion can occur many years following implantation of ICRS, even in eyes without pre-existing thinning or ectasia. The technique for explantation described herein can result in favorable clinical outcomes in such cases. These cases demonstrate the importance of long-term follow up of eyes that have undergone ICRS implantation.

Reshaping procedures for the surgical management of corneal ectasia

Corneal ectasia is a progressive, degenerative, and noninflammatory thinning disorder of the cornea. Recently developed corneal reshaping techniques have expanded the treatment armamentarium available to the corneal specialist by offering effective nontransplant options. This review summarizes the current evidence base for corneal collagen crosslinking, topography-guided photorefractive keratectomy, and intrastromal corneal ring segment implantation for the treatment of corneal ectasia by analyzing the data published between the years 2000 and 2014.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

[New therapeutic approach of keratoconus with intracorneal ring segments aided by femtosecond laser (Tecnolas Perfect Vision): indications, operating technique and results]

OBJECTIVE

To assess the results of intracorneal ring segment implantation assisted by the Tecnolas Perfect Vision(®) femtosecond laser (Heidelberg, Germany).

SETTINGS

Retrospective observational study.

METHODS

The patients were operated on with the Tecnolas Perfect Vision(®) femtosecond laser. The following parameters were evaluated before and after surgery: uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), corneal topography, wavefront analysis, and central corneal thickness. The Wilcoxon test was used for statistical analysis.

RESULTS

Seventeen eyes of 15 patients were included. The mean follow-up was 6.9±0.71 months. Significant improvement of UCVA and BCVA was observed in 82.35% (P=0.027) and 94.12% (P=0.003) of the eyes, respectively. The subjective refraction showed a significant decrease of the sphere from -10.29±5.54 to -6.5±5.03D (P=0.002). The subjective cylinder significantly decreased from 5.43±3.20 to 3.69±2.30D (P=0.026). The SAI also decreased significantly (P=0.011).

CONCLUSION

Femtosecond-assisted intracorneal ring segment implantation is an effective treatment for corneal ectasia. Further studies are needed to improve surgical parameters and outcomes.

Intrastromal corneal ring segments to correct low myopia in eyes with irregular or abnormal topography including forme fruste keratoconus: 4-year follow-up

PURPOSE

To report the 4-year outcomes after Intacs intrastromal corneal ring segment (ICRS) implantation to correct low myopia in patients with abnormal topography.

SETTING

Instituto de Microcirugia Ocular, Barcelona, Spain.

METHODS

This retrospective consecutive interventional case series included eyes with myopia lower than -4.50 diopters (D) and abnormal topography that excluded excimer laser surgery. Evaluation was performed preoperatively and at yearly intervals up to 4 years postoperatively. The 4-year outcomes measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, predictability and stability of refractive correction, the efficacy and safety indices, and complications.

RESULTS

After ICRS implantation, 82.05% of 39 eyes (21 patients) were within +/-1.00 diopter (D) of emmetropia and 46.15% were within +/-0.50 D. Refractive correction improved during the first 6 months and remained stable up to 4 years. The UDVA was 20/40 or better in all eyes and 20/20 or better in 38.46% of eyes. Seven eyes (17.95%) lost 1 line of CDVA, and no eye lost 2 or more lines. No intraoperative complications occurred. The ICRS were exchanged for thicker ICRS in 7 eyes (17.9%) because of undercorrection. One patient requested ICRS removal due to unsatisfactory refractive results.

CONCLUSIONS

The 4-year results indicate that ICRS implantation is effective and safe in the correction of low myopia in patients for whom excimer laser surgery is contraindicated because of abnormal topography, including forme fruste keratoconus. The achieved refractive correction remained stable throughout the follow-up.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Bilateral infectious keratitis after implantation of intrastromal corneal ring segments

PURPOSE

To report the development of bilateral infectious keratitis after implantation of intrastromal corneal ring segments (ICRSs).

DESIGN

Retrospective case report.

PARTICIPANTS

A 20-year-old woman presented with photophobia, decreased vision, and pain 11 days after uncomplicated implantation of ICRSs for keratoconus in both eyes. Bilateral corneal stromal infiltrates were noted at the site of ICRSs implantation.

INTERVENTION

The patient was started on frequent topical fortified antibiotics in both eyes. Despite aggressive medical management, stromal infiltrates progressed, necessitating removal of ICRSs from both corneas to control infectious keratitis and melting of cornea.

METHODS

Retrospective case report of a 20-year-old woman who developed bilateral severe infectious keratitis 11 days after uncomplicated implantation of ICRSs for keratoconus.

RESULTS

Cultures obtained at the time of initial presentation yielded Streptococcus viridans. Patient responded well to the treatment and was left with stromal scars in both corneas.

CONCLUSIONS

Although rare, simultaneous implantation of ICRSs may carry a risk of severe bilateral infectious keratitis. Early recognition of infection, aggressive treatment with antibiotics, and, in some cases, removal of ICRSs may be necessary to prevent serious sight-threatening complication of this refractive procedure.

One year outcome of manual alcohol-assisted removal of Salzmann's nodular degeneration

BACKGROUND

To analyze visual and refractive modifications and corneal topography changes in a patient treated for bilateral advanced Salzmann's nodular degeneration (SND).

METHODS

A forty-three-year-old man with bilateral advanced SND underwent manual, alcohol-assisted removal of the altered layer. Visual acuity, refraction, corneal topography and corneal aberrations were examined before and after the treatment after 7 days and 1, 6 and 12 months.

RESULTS

The uncorrected visual acuity changed from 0.1 to 1.0 in both eyes. Refraction changed from sphere +3.00 and cylinder +4.50 x 180 degrees in the right eye and sphere +6 and cylinder +4.0 x 170 degrees in the left eye to bilateral emetropia. Corneal topography recovered from an extremely flat profile to a normal shape and it was unvaried during the follow-up period. Main topographic indices, highly altered before the treatment, normalized and were normal at control examinations. The quality of vision improved significantly with reduction of high-order aberrations from RMS of 5,07 microm to 0,66 microm in the right eye and RMS of 4,89 microm to 0,57 microm in the left eye respectively.

CONCLUSIONS

Salzmann nodules produce an impressive central corneal flattening with high hyperopic refractive error and significant increment of corneal aberrations. After manual removal of the altered layer, the visual and refractive recovery, corneal topography and aberrometry normalization were immediate and stable during the observational period.

Long-term Follow-up of Intacs for Post-LASIK Corneal Ectasia

OBJECTIVE

To report long-term follow-up of Intacs microthin prescription inserts for the management of post-LASIK corneal ectasia.

DESIGN

Long-term (5 years), retrospective, nonrandomized study.

PARTICIPANTS

Eight eyes of 5 patients with post-LASIK corneal ectasia (3 men and 2 women) ages 31 to 54 years (mean age+/-standard deviation [SD], 41.60+/-9.24 years) who had completed 5 years of follow-up (mean follow-up +/- SD, 60.1+/-4.9 months; range, 57-68 months).

INTERVENTION

Two Intacs segments, inserted in the usual fashion, were used for low myopia correction (1 each nasally and temporally), with thickness based on the residual refraction of the patients.

MAIN OUTCOME MEASURES

Manifest refraction, uncorrected and best spectacle-corrected visual acuity, patient satisfaction, topography, and confocal microscopy analysis.

RESULTS

No intraoperative or late postoperative complications occurred in this series of patients. At 5 years, the SE error was statistically significantly reduced (pre-Intacs mean+/-SD, -5.47+/-2.66 diopters [D]; range, -11.50 to -3.00 D) to -2.56+/-3.44 D (range, -9.50 to 1.5 D; P = 0.01). At the end of the first postoperative year, refractive stability was obtained and remained stable during the follow-up period with no significant changes between the interval meantime (P>0.05). Pre-Intacs uncorrected visual acuity was 20/100 or worse in all eyes (range, counting fingers-20/100), whereas at the last follow-up examination, 6 (75%) of 8 eyes had uncorrected visual acuity of 20/40 or better (range, counting fingers-20/25). Two eyes (25%) maintained the pre-Intacs best spectacle-corrected visual acuity, whereas the rest of the eyes (6 eyes; 75%) experienced a gain of 1 or 2 lines. At the end of the first postoperative year, uncorrected and best-spectacle corrected visual acuity and topographic stability were obtained and were shown to have remained stable during the follow-up period with no significant changes between the interval meantime. Lamellar channel deposits were observed in confocal microscopy at or adjacent to the intrastromal ring segment.

CONCLUSIONS

Refractive stability was maintained for up to 5 years in the treatment of post-LASIK corneal ectasia after Intacs implantation. There was no evidence of progressive time-dependent corneal ectasia, late regression, or sight-threatening complications in this study.

Comparison of Topographic Corneal Irregularity After LASIK and Intrastromal Corneal Ring Segments in the Same Patients

PURPOSE

To retrospectively compare the irregularity of the corneal surfaces of 14 patients after LASIK in 1 eye and placement of intrastromal corneal ring segments (ICRS) in the other eye.

METHODS

In a within-patient comparison, Orbscan corneal topography was used to retrospectively compare the corneal surface irregularity of LASIK-treated and ICRS-treated eyes at an outpatient tertiary-care ophthalmology clinic in Sao Paulo, Brazil. For the anterior corneal surface, irregularity measurements were compared for both the central and peripheral areas of the cornea. The differences between each group were analyzed for statistical significance.

RESULTS

The corneal surfaces of eyes treated with ICRS were found to be more irregular than the corneal surfaces of eyes treated with LASIK, the mean irregularity being 1.91 for LASIK-treated eyes and 3.12 for ICRS-treated eyes in the anterior corneal surface and 0.51 for LASIK-treated eyes and 0.87 for ICRS-treated eyes in the posterior corneal surface. A statistically significant difference was noted only in the posterior surfaces.

CONCLUSIONS

When measured with Orbscan topography, ICRS-treated eyes show more corneal surface irregularity than LASIK-treated eyes. The difference in outcome for the two types of treatment may be due to the mechanical effect of the ICRS on the shape of the cornea.

Deep corneal neovascularization after implantation with intrastromal corneal ring segments

PURPOSE

To demonstrate the development of deep corneal neovascularization after intrastromal corneal ring segment (ICRS) implantation, and to demonstrate complete regression after treatment with surgical removal and anti-inflammatory therapy.

DESIGN

Observational case report.

METHODS

A 29-year-old man developed deep stromal neovascularization after ICRS implantation for post-laser-assisted in situ keratomileusis ectasia that was not associated with the surgical wound.

RESULTS

After surgical removal of the ICRS and treatment with topical prednisolone acetate 1.0% and cyclosporine A 1.0%, complete vessel regression occurred in 2 weeks.

CONCLUSIONS

ICRS can induce deep corneal neovascularization that is not associated with the surgical wound. Surgical removal of the intrastromal ring and treatment with topical anti-inflammatory agents can induce vessel regression.

Treating Keratoconus With Intacs Corneal Ring Segments

PURPOSE

To assess the safety and efficacy of Intacs inserts for the treatment of mild to moderate keratoconus.

METHODS

In a nonrandomized prospective clinical trial, 50 eyes of 37 patients with mild to moderate keratoconus were implanted with asymmetrical pairs of Intacs segments. Patients were interviewed and observed preoperatively and 24 hours, 1 week, 1, 3, 6, and 12 months postoperatively. Main outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, satisfaction with vision and trouble with vision, Visual Function-7 score, and surgically induced change in corneal astigmatism.

RESULTS

Of the 50 operations performed, 92% were successful. Mean follow-up was 6.3 +/- 3.2 months. In 4 (8%) eyes, both Intacs segments were removed. In addition, 7 refractive adjustments in 7 eyes were performed successfully to improve visual and surgical outcome. Both BSCVA and UCVA improved throughout follow-up. Visual functioning index improved from 61.6 +/- 21.1 to 80.8 +/- 22.5, and the percentage of satisfaction with vision improved from 24.3% to 87.5% at 12 months. Vector analysis of astigmatism correction showed that the mean change in corneal astigmatism was 2.9 +/- 2.9 D at 6 months postoperatively. By selecting patients in whom astigmatism correction was best (index of success >0.5), an analysis was performed to determine individual factors important in successful surgery. Preoperatively these 11 (22%) eyes did not differ significantly from the remaining eyes and the only significant value was low K readings in the flat axis.

CONCLUSIONS

Asymmetric Intacs placement improves BSCVA and UCVA and reduces astigmatism in patients with mild to moderate keratoconus. The procedure of Intacs placement is safe and effective. The change in astigmatism correction is unpredictable.

Intacs after laser in situ keratomileusis and photorefractive keratectomy

PURPOSE

To evaluate the efficacy of intrastromal corneal ring segments (Intacs, Addition Technology) for the correction of residual myopia after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

METHODS

In this prospective noncomparative case series, Intacs were implanted in 5 eyes (4 patients) that developed myopic regression after LASIK or PRK. Intacs were implanted a minimum of 11 months after the laser procedure. The technique was identical to the standard procedure for myopic unoperated eyes. The Intacs thickness was based on the amount of residual myopia.

RESULTS

Postoperative results revealed a reduction in the residual myopia and the mean K-reading. No eye lost best corrected Snellen visual acuity. No intraoperative or postoperative complications occurred.

CONCLUSIONS

Implantation of Intacs in eyes with myopic regression after LASIK and PRK resulted in a good refractive outcome and an improvement in uncorrected visual acuity.

Keratitis after implantation of intrastromal corneal ring segments

A 53-year-old man had implantation of 2 intrastromal corneal ring segments (Intacs, Addition Technology Inc.) in the left eye. Several days after the lower segment was exchanged, an infiltrate was present at the corneal incision site. This progressed to a lower channel infection followed by diffuse keratitis. Culture from the conjunctiva was positive for Staphylococcus epidermidis, but cultures from the cornea were negative for microorganisms. Later, 2 gas bubbles appeared at the interface. The patient was treated with topical and subconjunctival antibiotics and channel irrigation. The keratitis resolved, leaving a neovascularized opacity at the nasal part of the lower channel.

Videokeratography in Conductive Keratoplasty

PURPOSE

We used EyeSys videokeratography to evaluate corneal shape changes induced by conductive keratoplasty, a procedure that utilizes radio frequency energy to alter corneal shape to correct hyperopia.

METHODS

Follow-up data were available for 19 eyes (out of 24 eyes of 13 patients). Preoperative spherical hyperopia ranged from +0.75 to +3.25 D with astigmatism <0.75 D. Manifest refractive spherical equivalent refraction (MRSE), uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), topographical parameter predicted corneal acuity (PCA), corneal uniformity index (CU Index), regular astigmatism, total astigmatism, average simulated keratometry (Avg Sim K), effective refractive power, and asphericity were measured preoperatively and at 6 and 12 months postoperatively.

RESULTS

Twelve months postoperatively, mean PCA, CU Index, and BSCVA were maintained at preoperative levels. Mean UCVA (LogMAR) improved from 0.53+/-0.21 to 0.10+/-0.19 (P<.05) with a mean MRSE change from +1.62+/-0.76 D to -0.06+/-0.84 D (P<.05) from preoperative to 12 months postoperative. Mean asphericity increased +0.044+/-0.24 D (P>.05), mean Avg Sim K increased 1.88+/-0.72 D (P<.05), mean effective refractive power increased 1.71+/-0.79 D (P<.05), mean cylinder (cycloplegic refraction) increased 0.19+/-0.36 D (P<.05), mean regular astigmatism increased 0.25+/-0.49 D (P>.05), and mean irregular astigmatism decreased 0.01+/-0.13 D (P>.05) from preoperative to 12 months after conductive keratoplasty.

CONCLUSIONS

Avg Sim K and effective refractive power changes support the refractive results; 12-month postoperative maintenance of BSCVA, PCA, and CU Index suggest the procedure is safe. Conductive keratoplasty induced a slight regular astigmatism in some eyes, which decreased with time. The increase in mean corneal asphericity indicated possible induction of central and peripheral cornea changes.

Correction of spherical myopia with a single 150-degree intrastromal corneal ring segment

A 47-year-old woman with an uncorrected visual acuity (UCVA) of 20/70 and a refraction of -1.50 +0.75 x 75 in the right eye had 2 0.25 mm intrastromal corneal ring segments (Intacs) inserted uneventfully through a superior incision. The patient was hyperopic 2 years later with a refraction of +0.50 +0.75 x 25 and was intolerant of spectacles. She also complained of temporal glare. Twenty-seven months after insertion, the temporal ring segment was removed. Four months later, the UCVA was 20/20; with a refraction of plano +0.50 x 35, the visual acuity was 20/15. Topography showed corresponding regular astigmatism, and the patient's glare had resolved. Removal of 1 Intacs segment may be an option in cases of overcorrection after ring insertion for myopia.

Intacs for early pellucid marginal degeneration

A 42-year-old man had Intacs (Addition Technology Inc.) implantation for early pellucid marginal degeneration (PMD). Two Intacs segments (0.45 mm thickness) were inserted uneventfully in the fashion typically used for low myopia correction (nasal-temporal). Eleven months after the procedure, the uncorrected visual acuity was 20/200, compared with counting fingers preoperatively, while the best spectacle-corrected visual acuity improved to 20/25 from 20/50. Corneal topographic pattern also improved. Although the results are encouraging, concern still exists regarding the long-term effect of this approach for the management of patients with PMD.

Simple device for quantifying the influence of halos after lasik surgery

We present a simple device (called a halometer) to detect and quantify the phenomenon of halos after certain surgical procedures, such as refractive surgery. The task of the subject consists basically of discriminating, after dark adaptation, a small light source around a central high-luminance stimulus. The device, which is connected to a computer, provides a disturbance index to measure the effect of halos on the observer's vision. Tested with normal subjects and patients after LASIK (laser in situ keratomileusis) surgery, this apparatus proved sufficiently sensitive to quantify the halos in subjects who had undergone surgery.

Late bacterial keratitis after implantation of intrastromal corneal ring segments

We report a case of bacterial keratitis that occurred after implantation of intrastromal corneal ring segments (Intacs). The patient presented with decreased vision, inflammation, and stromal infiltrates localized at the extremity of an Intacs channel 3 months after surgery. Culture were positive for Clostridium perfringens and Staphylococcus epidermidis. The infiltrates progressed despite treatment with topical fortified and systemic antibiotics. The Intacs were removed. The keratitis slowly resolved, and the patient recovered a best corrected visual acuity of 20/20.

Management of keratoconus with Intacs

PURPOSE

To prospectively study the effects of the use of Intacs microthin prescription inserts for the management of keratoconus.

DESIGN

Prospective nonrandomized clinical trial.

METHODS

Thirty-three eyes of 26 keratoconus patients (17 males and 9 females) ages 21 to 51 years (mean age, 32 +/- 9.7 years) were included in the current study. All patients had clear central corneas and contact lens intolerance. Patients were excluded if any of the following criteria applied after the preoperative examination: previous intraocular or corneal surgery; history of herpes keratitis; diagnosed autoimmune disease; and systemic connective tissue disease. Two Intacs segments of 0.45-mm thickness were inserted in the cornea of each eye, aiming at embracing the keratoconus area to try to achieve maximal flattening. Preoperative examination included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, keratometric data, and corneal topography.

RESULTS

Intacs were successfully implanted in all eyes. In one eye Intacs were removed after 3 months because of their improper (superficial) placement. The follow-up ranged from 1 to 24 months (mean: 11.3 months). The mean UCVA significantly improved from 0.13 +/- 0.14 (range, counting fingers [CF]-0.5) to 0.39 +/- 0.27 (range, CF-1.0) (P <.01). Of 33 eyes, 2 eyes lost 1 line of UCVA, and 3 eyes maintained the preoperative UCVA, whereas the rest (28 eyes) experienced a 1- to 10-line gain. The mean BCVA also improved from 0.47 +/- 0.31 (range, CF-1.0) to 0.64 +/- 0.26 (range, 0.1-1.0) (P <.01). Of 33 eyes, 4 eyes experienced 1- to 2-line loss of BCVA, 4 eyes maintained the preoperative BCVA, whereas the rest (25 eyes), experienced a 1- to 6-line gain. Of 3 patients (3 eyes) with unsatisfactory results, 1 patient improved with one segment removal and in 2 patients the segments were permanently removed. One of these eyes underwent successful PKP.

CONCLUSIONS

With mean follow-up of 11.3 months, intracorneal ring segments implantation improved UCVA and BCVA in the majority of the keratoconus patients. Even though the results are encouraging, concern still exists regarding the predictability as well as the long-term effect of such an approach for the management of keratoconus.

Ferrara intrastromal corneal rings for the correction of keratoconus

PURPOSE

To evaluate the safety and efficacy of Ferrara intrastromal corneal rings in the treatment of eyes with keratoconus without central corneal scarring.

SETTING

Vlemma Eye Institute, Athens, Greece.

METHODS

Twenty-six patients with bilateral keratoconus, clear central corneas, and contact lens intolerance participated in the study. Videokeratographic corneal topography and ultrasonic pachymetry were performed in all eyes to identify the cone area and to select the thickness of the segments to be implanted, respectively. Ferrara intrastromal corneal rings were implanted around the center of the cone in 1 eye of each patient.

RESULTS

The minimum follow-up after ring implantation was 6 months. In 2 cases, the rings had to be removed early in the postoperative period because of superficial implantation in 1 patient and asymmetrical placement in the other. The rest of the operated eyes demonstrated a reduction in astigmatism and spherical correction and improved uncorrected visual acuity. No eye lost best corrected visual acuity.

CONCLUSIONS

Ferrara intrastromal corneal rings reduced corneal steepening and normalized the central cornea in eyes with keratoconus. Ferrara ring implantation was a safe procedure that may be considered in patients who are unable to have other surgical techniques, particularly contact-lens-intolerant keratoconus patients whose only option is corneal transplantation.

Corneal asphericity after hyperopic laser in situ keratomileusis

PURPOSE

To analyze corneal asphericity after hyperopic laser in situ keratomileusis (LASIK) and its relationship to the clinical outcomes.

SETTING

Corneal and Refractive Surgery Service, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA.

METHODS

In a retrospective case series, 23 patients (33 eyes) with hyperopia or hyperopic astigmatism who had LASIK were evaluated. A computer program (Holladay Diagnostic Summary, EyeSys Laboratories) was used to analyze corneal asphericity (Q) before and after LASIK. Corneal asphericity was evaluated to determine the association with the postoperative refractive error, best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), achieved refractive correction, mean corneal power (K), refractive yield (achieved/attempted correction), and keratometric yield (change in keratometry/attempted correction).

RESULTS

After hyperopic LASIK, all corneas exhibited increased negative central Q. The postoperative corneal radius of curvature, BSCVA, and refractive and keratometric yields were not significantly correlated with the preoperative Q values. The asphericity change, Delta Q, was highly correlated with the achieved correction (r = 0.747, P <.0001). The postoperative Q value correlated well with the preoperative value (r = 0.534, P <.05) and the achieved correction (r = 0.601, P <.05) but not with the Delta Q. Neither the postoperative Q nor the Delta Q was correlated with the spherical equivalent, K, BSCVA, or UCVA.

CONCLUSIONS

Asphericity may be a useful quantitative descriptor of the corneal optical contour after hyperopic LASIK. Negative central Q increased after hyperopic LASIK, especially when greater degrees of refractive correction were attempted.

Risk factors for self-reported visual symptoms with Intacs inserts for myopia

OBJECTIVE

Potential risk factors and visual performance measures were evaluated for relationship to self-report of clinical visual symptoms after the refractive procedure for placement of Intacs microthin prescription inserts for myopia.

DESIGN

Retrospective nonrandomized comparative study.

PARTICIPANTS/INTERVENTION

Patients were participants in the U.S. Food and Drug Administration phase III KeraVision prospective clinical trials.

MAIN OUTCOME MEASURES

Study participants (n = 263) were retrospectively classified into one of three outcome groups on the basis of postoperative self-reported visual symptoms and/or request for Intacs inserts removal through month 24. Differences between outcome groups in visual acuity, refractive error, corneal geometry, corneal topography, type of preoperative corrective lens wear, and demographic variables were evaluated with multivariate logistic regression.

RESULTS

Clinical trial participants who had preoperative mean keratometry >45 diopters (D) (adjusted odds ratio [OR], 0.43; 95% confidence interval [CI], 0.21, 0.85, P = 0.02), manifest refractive astigmatism of 0.75 D or 1.00 D (adjusted OR, 0.52; 95% CI, 0.25, 1.08, P = 0.08), measured uncorrected visual acuity > or =2 lines better than that predicted by their respective cycloplegic refractive error (adjusted OR, 0.39; 95% CI, 0.14, 1.12, P = 0.08) and/or had worn soft contact lenses (adjusted OR, 0.58; 95% CI, 0.32, 1.04, P = 0.07) tended to be less likely to report postoperative clinical visual symptoms with Intacs inserts. Risk of clinical visual symptoms and request for Intacs inserts removal approximately doubled for each 0.50 D of additional postoperative defocus equivalent (crude OR, 1.86; 95% CI, 1.39, 2.48, P = 0.00). Controlling for postoperative defocus and important preoperative risk factors, subjects who reported significant clinical visual symptoms were more likely to have had preoperative uncorrected visual acuity that was worse than that predicted by their respective cycloplegic refractive error (adjusted OR, 1.84; 95% CI, 0.98, 3.42, P = 0.06). Risk of reporting clinical visual symptoms was increased with mesopic pupil diameter > or =6.5 mm (adjusted OR, 1.76; 95% CI, 0.96, 3.24, P = 0.07). Within the group of patients who reported postoperative clinical visual symptoms, 71 of 122 (58%) had ceased reporting them by month 24.

CONCLUSIONS

Adjusting for important risk factors simultaneously, this study suggested that certain preoperative characteristics may increase or decrease the likelihood, depending on the characteristic, of refractive surgery candidates to report significant clinical visual symptoms with Intacs inserts.

Intrastromal corneal ring segments for low myopia: a report by the American Academy of Ophthalmology

OBJECTIVE

This document describes intrastromal corneal ring segments (Intacs) inserts technology and examines the evidence to answer the key question about whether the treatment is safe and effective in correcting low myopia.

METHODS

A literature search that was conducted in September 2000 retrieved 13 relevant citations, and the reference lists of these articles were consulted for additional citations. Panel members reviewed this information and articles were rated according to the strength of evidence.

RESULTS

Prospective multicenter phase II and III clinical trials (Level II evidence rating) of Intacs inserts for myopia of -1.00 to -3.00 diopters (D), with a maximum of +1.00 D of astigmatism, enrolled a total of 452 subjects, with a total of 454 surgical attempts. The results from phase II and phase III were pooled for much of the analysis. At 1 year, 97% of patients who completed follow-up had 20/40 or better uncorrected visual acuity (UCVA). Seventy-four percent of patients had 20/20 or better UCVA. Ninety-two percent of eyes were within +/-1 D of intended refractive correction, and 69% were within 0.5 D of intended refractive correction. At 3 months, 90% of patients had less than 1.0 D of change from the previous examination performed at 1 month. The ocular complication rate, which was defined as clinically significant events but not resulting in permanent sequelae, was 11% at 12 months. The adverse event rate was 1.1%, defined as a serious event if untreated. Nearly 9% of patients requested to have their inserts removed and a total of 3.8% of patients required a secondary surgical intervention.

CONCLUSIONS

To date, evidence suggests that low myopia (-1 to -3 D) in a well-defined group of patients who have a stable manifest refraction and less than +1.0 D of astigmatism can be treated with Intacs inserts with a reasonable assurance of safety and effectiveness. Additional clinical research is needed to determine the long-term effectiveness of treatment and the comparative safety, effectiveness, and costs with other treatment modalities, including laser-assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

Long-term follow-up of Intacs from a single center

PURPOSE

To evaluate the long-term visual results in patients having Intacs placement for the correction of mild myopia.

SETTING

Department of Ophthalmology, Mount Sinai School of Medicine and the Mount Sinai Hospital of Mount Sinai NYU Health, New York, New York, USA.

METHODS

Patients with mild myopia (spherical equivalent between -0.75 and -4.50 diopters [D]) were enrolled to have Intacs placement between May 1995 and March 1999 under United States Food and Drug Administration Phase II and Phase III clinical trials for intrastromal corneal ring segments (ICRS). Six insert thicknesses were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results evaluated were uncorrected visual acuity (UCVA), maintenance of best spectacle-corrected visual acuity (BSCVA), predictability and stability of the refractive effect, induced manifest refraction cylinder, slitlamp findings, self-reported visual symptoms, and maintenance of mesopic contrast sensitivity.

RESULTS

One hundred fourteen eyes of 73 patients were enrolled; 113 eyes of 72 patients received Intacs. There were no serious intraoperative or postoperative complications. The mean follow-up was 17.5 months +/- 8.9 (SD). At the end of this period (number of eyes evaluated = 100), the UCVA was 20/40 or better in 95 eyes (95.0%), 20/20 or better in 72 (72%), and 20/16 or better in 41 (41%). None of the 113 eyes lost 10 or more letters or 2 or more lines of preoperative BSCVA. The mean change in the cycloplegic refraction spherical equivalent for the 6 insert thicknesses was as follows: -0.75 +/- 0.00 D for 0.21 mm; -1.17 +/- 0.42 D for 0.25 mm; -2.00 +/- 0.54 D for 0.30 mm; -2.59 +/- 0.53 D for 0.35 mm; -3.09 +/- 0.54 D for 0.40 mm; and -3.82+/-0.80 D for 0.45 mm. The refractive correction was within +/-1.0 D of the predicted outcome in 103 eyes (92.0%) and within +/-0.5 D in 72 eyes (63.7%). Intacs were removed from 6 eyes (5.3%). All 4 eyes for which data were available 3 months after removal returned to within +/-0.5 D of their preoperative manifest refraction spherical equivalent. Intacs were exchanged because of undercorrection in 2 eyes (1.8%). These eyes gained 3 and 5 lines of UCVA 12 months and 18 months, respectively, after the exchange procedure. Overall, 85.7% (36/42) of the patients were satisfied with the results of the Intacs procedure.

CONCLUSION

Intacs safely and effectively corrected mild myopia. Placement is a brief, easy outpatient procedure. The refractive effect was predictable and stable over long-term follow-up. Results from a limited number of removal and exchange procedures indicate that Intacs are removable and adjustable.