Laser in situ keratomileusis versus long-term contact lens wear: Decision analysis

Reasons for not performing surface ablation refractive surgery in Saudi population

PURPOSE:

The primary goal of this study is to analyze the reasons why refractive surgery was not performed for candidates who requested the procedure among single eye-clinic visitors in Saudi Arabia. Secondarily, we aimed to determine the corneal parameters that are characteristic of Saudi population and to figure out the relationship between the magnitude of central corneal thickness and the degree of myopia.

METHODS:

A retrospective data was collected for all patients who presented to a single-surgeon eye clinic at King Abdul Aziz Medical City-National Guard, Saudi Arabia, seeking refractive surgery between January 2010 and December 2015.

RESULTS:

Unstable refraction (21.78%) followed by amblyopia with unrealistic expectations (18.75%) and high myopia (15.62%) were the most common reasons not to proceed with refractive surgery in the included sample. The mean central corneal thickness for all patients included in this study was (538 μm ± 32.6). We found no significant relationship between central corneal thickness and the degree of myopia OD [rs(178) = −0.017, P = 0.823] and OS [rs(182) = 0.016, P = 0.831] for right and left eyes, respectively.

CONCLUSION:

Unstable refraction followed by amblyopia with unrealistic expectations and high myopia were the leading causes not to perform refractive surgery in this study. No significant relationship can be figured out between central corneal thickness and the degree of myopia.

The risk of vision loss in contact lens wear and following LASIK

PURPOSE

To compare the risk of vision loss following contemporary laser-assisted in situ keratomileusis (LASIK) with different types and modality of use of contact lenses.

METHODS

Data from a previously published study were used to derive the incidence of vision loss (≥ 2 line loss of best corrected spectacle acuity) following microbial keratitis for different contact lens types and wearing modality, stratified by duration of lens wear. A literature search on vision loss following LASIK was performed between 2003 and 2019. The prevalence of vision loss at six months post-surgery was captured from clinical trials published after 2003. A proportion meta-analysis was applied to derive the prevalence of vision loss following LASIK. A least-squares fitting of cumulative vision loss (P, /10 000 wearers) over time (t, years) using an exponential model estimated the years of contact lens wear to which the risk of vision loss with LASIK was equivalent.

RESULTS

Vision loss following LASIK occurred in 66 (95% confidence interval [CI] 34-108) per 10 000 wearers. As a conservative estimate based on the lower confidence interval of the estimated equivalent years of contact lens wear, daily wear contact lenses and extended overnight silicone wear hydrogel contact lens need to be worn for 103 (95% [CI] 103-391) and 25 (95% [CI] 25-79) years respectively, to equal the rate of vision loss equivalent to a one-off LASIK procedure.

CONCLUSIONS

The risk of vision loss to the individual is low with either contact lens wear or refractive surgery. Contact lens wear does not pose a higher risk of vision loss than LASIK surgery for the most common wear modalities.

Risk for microbial keratitis: Comparative metaanalysis of contact lens wearers and post-laser in situ keratomileusis patients

PURPOSE

To compare the risk for microbial keratitis in contact lens wearers stratified by wear schedule with the risk after laser in situ keratomileusis (LASIK).

SETTING

Hamilton Eye Institute and Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, USA.

DESIGN

Comparative metaanalysis and literature review.

METHODS

An extensive literature search was performed in the PubMed database between December 2014 and July 2015. This was followed by a metaanalysis using a mixed-effects modeling approach.

RESULTS

After 1 year of daily soft contact lens wear, there were fewer microbial keratitis cases than after LASIK, or approximately 2 cases fewer cases per 10 000 (P = .0609). If LASIK were assumed to have essentially a 1-time risk for microbial keratitis, 5 years of extrapolation would yield 11 more cases per 10 000 with daily soft contact lens wear than with LASIK, or approximately 3 times as many cases (P < .0001). The extended use of soft contact lenses led to 12 more cases at 1 year than LASIK, or approximately 3 times as many cases (P < .0001), and 81 more cases at 5 years (P < .0001). When incorporating an estimated 10% retreatment rate for LASIK, these results changed very little.

CONCLUSIONS

Microbial keratitis is a relatively rare complication associated with contact lens use and LASIK postoperatively. The risk for microbial keratitis was similar between patients using contact lenses for 1 year compared with LASIK. Over time, the risk for microbial keratitis was higher for contact lens use than for LASIK, specifically with extended-wear lenses.

[Avoidance and management of complications in laser in situ keratomileusis]

Laser in situ keratomileusis (LASIK) is now considered to be a safe and effective standard procedure for surgical correction of low to medium ametropia. Nevertheless, as in any other surgical intervention complex courses may occur in single rare cases. Possible complications include, but are not limited to, optically effective errors, such as too small or decentered optical zones as well as intraoperative flap cutting errors and postoperative complications, such as inflammation (e.g. diffuse lamellar keratitis, DLK), epithelial or flap folds, epithelial ingrowths or iatrogenic ectasia. Compliance to standards for indications and treatment based on the current scientific knowledge can significantly reduce the occurrence of complications. These standards include adjustment of the optical zone to the mesopic pupil diameter, the application of state of the art eye trackers, careful performance of intraoperative and postoperative procedures by a surgeon experienced in the entire spectrum of ocular surgery, the possibility of treating complications directly on occurrence and, last but not least, conservative patient selection and choice of treatment.

Microbial keratitis after corneal laser refractive surgery

Corneal laser refractive surgery is increasingly being performed on patients with the aim of improving unaided vision. Most candidates for surgery have excellent spectacle- or contact lens-corrected vision. Although microbial keratitis following refractive surgery is a rare complication, and usually has a good visual outcome, it can be sight-threatening. The spectrum of pathogens differs to other causes of microbial keratitis, such as contact lens-associated keratitis, and a different management approach is required. Postoperatively, patients are prescribed topical steroids and broad-spectrum topical antibiotics, typically fluoroquinolones. These do not cover unusual organisms, such as fungi, Nocardia, Acanthamoeba and some atypical mycobacteria. In post-laser-assisted in situ keratomileusis microbial keratitis, the lamellar flap should be lifted to acquire samples for specific microbiological examination, including these atypical organisms. Confocal microscopy is a noninvasive test that provides morphological information, and is operator dependent, but may assist in the rapid diagnosis of fungal, Acanthamoeba or Norcardia keratitis. PCR is not in widespread use, but has high sensitivity and specificity, and may facilitate early diagnosis and specific treatment of the causative organism, which is critical in obtaining the best clinical outcome.

Reasons for not performing LASIK in refractive surgery candidates in Yemen

PURPOSE

To determine and analyze the reasons that laser in situ keratomileusis (LASIK) was not performed in patients who requested refractive surgical correction of their refractive errors.

METHODS

A retrospective observational study was performed in Yemen Magrabi Hospital between June 2005 and October 2006; the case records of 1596 new consecutive patients who presented for refractive surgery at our refractive surgery unit were reviewed. Data on the ocular status, refractive problems, and investigations performed were analyzed. The reasons for not performing LASIK in the cases that were rejected were recorded and analyzed.

RESULTS

A total of 1191 patients (74.6%) were advised to have LASIK of the 1596 patients examined. LASIK was not advised in 405 patients (25.4%). The most common reasons for rejecting LASIK were suboptimal central corneal thickness (25.9%), high myopia >-11.00 D (17.0%), keratoconus (15.5%), cataract (11.4%), and suspicious corneal topography (forme fruste keratoconus) (9.4%).

CONCLUSIONS

Patients who request refractive surgery have a variety of problems and attention must be given to these patients. Suboptimal corneal thickness, high amount of refractive error, and keratoconus were found to be the leading causes of not performing LASIK in Yemeni patients.