LASIK Flap: Postoperative Complications

Transepithelial photorefractive keratectomy: a prospective randomized comparative study between the two-step and the single-step techniques

OBJECTIVES

To assess and compare the six-month outcome of the two-step transepithelial phototherapeutic keratectomy- photorefractive keratectomy (PTK-PRK) and the single-step transepithelial PRK for myopia and myopic astigmatism.

METHODS

A prospective randomized study. The study enrolled 100 eyes of 50 patients with mild to moderate myopia or myopic astigmatism stratified into two groups, PTK-PRK (n = 50 eyes) and single step PRK (n = 50 eyes). Primary outcome measures were visual acuity and manifest refraction. Secondary outcome measures were epithelial healing duration, post-PRK pain scores and 3-month postoperative haze grading.

RESULTS

Preoperative characteristics were similar in both groups (p value > 0.05). The mean uncorrected distance visual acuity (UDVA) at 1 week, 1 month, 3 and 6 months was significantly better in the single-step PRK group than in the two-step PTK-PRK group (p < 0.001). The mean manifest sphere, cylinder and spherical equivalent showed a significant difference at all follow up visits in favour of the single-step PRK (p value < 0.001). Epithelial healing duration was faster in single-step PRK (p value < 0.001). Pain scores were significantly lower following single-step PRK at 8 h, 1 day, 3 days (p value < 0.001) but were similar at the 7th day. Haze scores showed no statistical difference between the two groups at 3-month follow-up.

CONCLUSION

The two transepithelial PRK techniques were effective in correcting mild to moderate myopia and myopic astigmatism. However, Single-step transepithelial PRK achieved faster visual recovery, better refractive outcome and shorter epithelial healing time with less post-PRK pain.

CLINICAL TRIALS REGISTRY

(Clinical Trials.gov Identifier): NCT04710082.

Early LASIK flap displacement without signs of infection

A 37-year-old woman was referred for refractive surgery evaluation. Poor visual quality in her left eye is her chief concern. The patient had undergone laser in situ keratomileusis (LASIK) in both eyes 3 days previously. Detailed history revealed that the patient underwent surgery to correct low myopia and astigmatism (-2.50 -2.75 × 180 in the right eye and -1.25 -2.75 × 180 in the left eye). The preoperative evaluation corrected distance visual acuity (CDVA) was 20/20 in the right eye and 20/20 in the left eye. The surgery was performed with a mechanical microkeratome and was uneventful. The patient reports that after her vision improved on the first day, she woke up with blurry vision in her left eye on the second day and it remained that way until the third day when she sought medical help. The slitlamp examination showed LASIK flap displacement without signs of infection ( Figure 1JOURNAL/jcrs/04.03/02158034-202212000-00023/figure1/v/2022-12-01T092452Z/r/image-tiff ). The patient was using topical corticosteroids and topical antibiotics every 6 hours. Considering the likely stromal exposure time, what would be the best approach for this case? Does the probable time of displacement of this flap change its behavior? In what way? If you decide to reposition the flap, would it be interesting to use fibrin glue or suture? Considering that there was no major trauma in the patient's report, what is the importance of the LASIK flap having been created by a mechanical microkeratome and not by a femtosecond laser in the displacement of the flap?

Influence of Preoperative Keratometry on Refractive Outcomes for Myopia Correction With Small Incision Lenticule Extraction

PURPOSE

To evaluate the effect of preoperative keratometry on refractive outcomes after small incision lenticule extraction (SMILE) for myopia.

METHODS

This retrospective study comprised 515 consecutive eyes that had SMILE to correct myopia. Pearson correlation and linear regression were used to determine the relationship between residual spherical equivalent and preoperative keratometry. The same analyses were repeated in the quartiles with the lowest and highest preoperative myopia.

RESULTS

Preoperatively, the mean spherical equivalent was -5.67 ± 1.87 diopters (D) (range: -1.63 to -9.75 D) and the mean keratometry was 43.10 ± 1.30 D (range: 38.90 to 47.00 D). Three months postoperatively, the mean spherical equivalent was -0.07 ± 0.18 D. After adjustment for age, sex, and preoperative spherical equivalent, greater postoperative undercorrection occurred in eyes with steeper corneas (P = .001). Each diopter of steeper keratometry resulted in 0.52% (0.03 D) more undercorrection. Correlation between the mean preoperative keratometry and residual spherical equivalent was significant in the lower preoperative myopia group (r = -0.24, P = .006), but not significant in the higher myopia group (r = -0.02, P = .809).

CONCLUSIONS

Preoperative keratometry affects refractive outcomes after SMILE. Steeper corneas have greater undercorrection, especially in eyes with low myopia. Knowledge of the correlation between refractive outcomes of SMILE and keratometry would help in modifying current treatment algorithms. [J Refract Surg. 2020;36(6):374-379.].

Traumatic displacement of laser in situ keratomileusis flaps: an integrated clinical case presentation

Background

Traumatic dislocation of laser-assisted in situ keratomileusis (LASIK) corneal flaps is an uncommon postoperative complication that could occur any time after LASIK, and could be visually devastating. We evaluated the visual outcomes, corneal sensation, tear function, and dry eye questionnaire results of patients with traumatic dislocation of LASIK flaps, including one LASIK flap amputation.

Methods

This is a retrospective case series. Seven patients who were diagnosed with traumatic displacement of the LASIK flap and underwent flap replacement surgery between August 2014 and January 2019 were included.Patient’s visual acuity, refraction, corneal sensitivity, non-invasive tear breakup time (NIBUT), tear meniscus height (TMH), and ocular surface disease index (OSDI) results were evaluated.

Results

The patients’ mean age was 35.86 ± 5.84 years, and 42.9 % (3/7) were male. The mean duration from LASIK to trauma was 8.86 ± 2.48 years.The mean preoperative and postoperative six-month corrected distance visual acuity (CDVA) were 0.55 ± 0.34 and 0.02 ± 0.03, respectively. The mean spherical equivalent and astigmatism at six months postoperatively was − 1.0 ± 0.95 D and − 0.5 ± 0.25 D, respectively. The corneal flap was clear and well-positioned at the final follow-up (mean: 28.57 ± 6.9 months). 85.71 % (6/7) of the patients showed worse corneal sensation in the injured eye. Interocular OSDI discrepancy was less in those whose last visit was more than 30 months after the trauma.

Conclusions

Postoperative CDVAat six months was improved, and the refractive data also showed some improvement. The corneal nerve and tear function recovery peaked before 30 months, while the OSDI continued to show a strong trend of improvement beyond 30 months.

Incidence of Intraoperative and Early Postoperative Adverse Events in a Large Cohort of Consecutive Laser Vision Correction Treatments

PURPOSE

To evaluate the incidence of adverse events (AE) following laser vision correction.

DESIGN

Retrospective case series.

METHODS

Optical Express, UK. Patients/study population: patients who underwent laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between July 1, 2014, and June 30, 2016. Intervention/observation procedures: all AEs recorded in the electronic medical record were extracted and retrospectively reviewed. The total incidence of AE and serious adverse events (SAE) was calculated. Loss of 2 or more lines of corrected distance visual acuity (CDVA) was calculated for the entire cohort of patients that attended a minimum of 3 months follow-up.

MAIN OUTCOME MEASURES

AEs; Preoperative and last available postoperative clinical data.

RESULTS

A total of 31,921 (61,833 eyes) were included in the study for LASIK and 5,016 (9,467 eyes) for PRK. The total number of AE was 850 for LASIK (occurring in 783 eyes of 657 patients; incidence of 1.3% or 1:79 eyes) and 227 for PRK (occurring in 218 eyes of 170 patients; incidence of 2.3% or 1:43 eyes). In the LASIK group, there were 287 SAEs (271 eyes of 226 patients; incidence of 0.4% or 1:228 eyes), and the number of SAEs in PRK group was 65 (65 eyes of 39 patients; incidence 0.7% or 1:146 eyes). Combining LASIK and PRK data, the loss of 2 or more lines of CDVA was recorded in 0.37% of eyes.

CONCLUSIONS

Contemporary LASIK and PRK are safe procedures with a low incidence of serious adverse events.

A Multicenter Retrospective Survey of Refractive Surgery in 78,248 Eyes

PURPOSE

To retrospectively evaluate the current practice, trends, and outcomes of refractive surgery in Japan.

METHODS

This multicenter survey comprised 78,248 eyes of 39,727 consecutive patients who underwent refractive surgery at 45 major institutions in Japan. The corresponding ophthalmologists responded to a selfadministered questionnaire. The authors especially evaluated the safety, efficacy, predictability, stability, and adverse events of LASIK and phakic intraocular lens (IOL) implantation 3 months postoperatively.

RESULTS

The most common refractive surgery was LASIK (90.9%), followed by corneal inlay (5.0%), posterior chamber phakic IOL implantation (1.3%), laser-assisted subepithelial keratomileusis (1.0%), refractive lens exchange (0.9%), photorefractive keratectomy (0.3%), and refractive lenticule extraction (0.2%). For subgroup analysis, 69,987 eyes (99.5%) and 67,512 eyes (95.9%) achieved corrected and uncorrected distance visual acuity of 20/20 or better, respectively, after LASIK, and 935 eyes (98.8%) and 890 eyes (94.1%), respectively, after phakic IOL implantation. There were 69,176 eyes (98.3%) and 908 eyes (96.0%) within ±1.00 diopter (D) of the attempted correction after LASIK and phakic IOL implantation, respectively. There were 1,926 eyes (2.7%) and 1 eye (0.1%) with changes in refraction of 1.00 D or less from 1 week to 3 months after LASIK and phakic IOL implantation, respectively. No vision-threatening complications occurred in any case.

CONCLUSIONS

According to this survey, LASIK remains the most prevalent surgical technique in Japan. Both LASIK and phakic IOL implantation offered good safety and efficacy outcomes, yielding predictable and stable results. [J Refract Surg. 2017;33(9):598-602.].

A pilot study: LASEK with the Triple-A profile of a MEL 90 for mild and moderate myopia

Background

To investigate the visual and refractive outcomes in patients with mild to moderate myopia after laser-assisted subepithelial keratectomy (LASEK) using the 500 Hz pulse rate of the Triple-A profile.

Methods

Thirty-six eyes of 20 patients (mean age, 27.5 ± 4.6 years) were included in this prospective, consecutive study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal topography, and corneal aberrations were measured preoperatively and 1 day, 1 week, 1, 3 and 6 months post-operation.

Results

At 1 week after surgery, UDVA was better than or equal to 20/25 in all eyes. At postoperative 6 months, the efficacy and safety index was 1.05 ± 0.13 and 1.12 ± 0.15, respectively; all eyes had a UDVA of 20/20 or better, and no eyes showed a loss in CDVA; 100% of the eyes were within ±1.00 D of the attempted spherical equivalent (SE) correction.

Conclusion

The postoperative results indicate that using the Triple-A ablation profile of the MEL 90 excimer laser with a 500 Hz pulse rate is a safe, efficient, and predictable method to correct mild to moderate myopia.

Refractive error in underserved adults: causes and potential solutions

PURPOSE OF REVIEW

To evaluate the epidemiology of uncorrected refractive errors (URE) in adults both in the United States and globally, health outcomes impacted by URE, common barriers to treatment, and propose potential interventions.

RECENT FNDINGS

URE is the main cause of visual impairment and the second leading cause of blindness globally. Rates of URE are rising, and cause disability that reduces productivity, economic earnings, and the quality of life of affected individuals. Economic barriers, healthcare access, and sociocultural constraints are among the most fundamental barriers to correcting URE. However, innovative approaches are poised to lower rates of URE.

SUMMARY

URE is a leading cause of preventable visual impairment with serious health consequences. Numerous social and financial barriers are associated with the high prevalence of URE in low-income adults. Novel delivery programs for eyeglasses and programs to provide refractive surgery to correct refractive error could decrease rates of URE.