Dry Eyes After SMILE

Randomized controlled trial on corneal denervation, neuroinflammation and ocular surface in corneal lenticule extraction for advanced refractive correction (CLEAR) and small incision lenticule extraction (SMILE)

BACKGROUND

To investigate and compare the corneal denervation, tear neuromediators, and ocular surface changes following corneal lenticule extraction for advanced refractive correction (CLEAR) versus small incision lenticule extraction (SMILE).

METHODS

In this randomized clinical trial, 19 patients were randomized to undergo CLEAR in one eye and SMILE in the other eye. Ocular surface assessments, in vivo confocal microscopy for seven corneal nerve parameters, four corneal dendritic cell parameters, three corneal epithelial parameters, and tear neuromediator analysis were performed preoperatively and 1, 3, 6 and 12 months postoperatively.

RESULTS

There were no significant differences in all ocular surface assessments between CLEAR and SMILE throughout postoperative 1 year. CLEAR and SMILE led to significant and comparable reductions of corneal nerve fiber density (CNFD), nerve branch density, total branch density, nerve fiber length, area, and fiber fractal dimension, which did not restore even at 1 year. The reduction in CNFD was significantly correlated with the corrected spherical equivalent in both surgical types. Although post-SMILE eyes had significantly higher nerve growth factor concentrations at 1 month, there was no significant difference in substance P and calcitonin gene-related peptide (CGRP) concentrations between SMILE and CLEAR.

CONCLUSIONS

CLEAR and SMILE had comparable effects on ocular surface, corneal denervation and postoperative neuroinflammation. Corneal nerve metrics did not restore even at 1 year for both procedures.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT06774651, registration on 14 January 2025, https://clinicaltrials.gov/study/NCT06774651 .

The effect of preoperative total antioxidant capacity on short-term outcomes after kerato-lenticule extraction surgery

To evaluate influence of total antioxidant capacity expression (TAC) on outcome of kerato-lenticule extraction (KLEx). A prospective non-randomized trial was conducted and patients received KLEx were categorized via TAC concentration. A total of 56 and 36 eyes were enrolled into the low TAC and high TAC groups. The main outcomes are the postoperative un-corrected visual acuity (UCVA), refraction and superficial keratitis between groups. The generalized liner model was applied for statistical analysis. One month after the KLEx surgery, the UCVA was significantly higher in the high TAC group (P = 0.028), and low TAC group associated with superficial keratitis risk compared to high TAC group (P = 0.035). The trends of TAC and ascorbic acid (AA) decrements were more significant in the low TAC group (both P < 0.05). Low TAC population and old age correlated to poor UCVA (both P < 0.05) while the thick CCT correlated to better UCVA (P = 0.030). Besides, the low TAC population (P = 0.032) correlated to higher superficial keratitis rate, while old age (P = 0.018) correlated to lower superficial keratitis rate. The presence of low TAC expression correlated to worse UCVA and higher risk of superficial keratitis after KLEx.

The Efficiency, Predictability and Safety Between Custom-Q Femotsecond Laser In Situ Keratomileusis and Second (Visumax 800) Generation Keratorefractive Lenticule Extraction Surgery

Background/Objectives: To evaluate the postoperative outcomes between the second-generation keratorefractive lenticule extraction (KLEx) surgery and femtosecond laser in situ keratomileusis (FS-LASIK). Methods: A retrospective cohort study was conducted and subjects received second-generation KLEx and FS-LASIK surgeries were enrolled. A total of 124 and 102 eyes were selected into the second-generation KLEx and FS-LASIK groups after exclusion. The primary outcomes were the postoperative uncorrected distance visual acuity (UDVA), spherical equivalent (SE), amount of astigmatism, and best-correct visual acuity (BCVA). The independent t-test was applied to compare the primary outcomes between groups. Results: The mean UDVA three months postoperatively showed insignificant differences between the two groups (p = 0.999). At the final visit, there were 113 (91.12%) and 96 (94.12%) subjects who reached UDVA 20/20 in the FS-LASIK and second-generation KLEx groups and the difference was statistically insignificant (p = 0.455), and the second-generation KLEx group illustrated a higher UDVA improvement (p = 0.046). The SE three months postoperatively showed insignificant difference between groups, whether the absolute value or the ratio of SE within ±0.50 D or ±1.00 D (all p > 0.05). The vector analysis indicated that the difference vector (DV) was significantly lower in the second-generation KLEx group (p = 0.033). The ratio of loss of more than 1 line BCVA showed insignificant differences between the two groups (all p > 0.05). In addition, the risk of postoperative dry eye disease (DED) was significantly higher in the FS-LASIK group (p = 0.031). Conclusions: The efficiency and predictability between second-generation KLEx and FS-LASIK surgeries are similar, while more DED occurred after FS-LASIK surgery.

Early clinical outcome with lens position adjustment following implantable collamer lens surgery

AIM

To observe early clinical outcome with lens position adjustment following the implantable collamer lens (ICL) surgery.

METHODS

Sixty patients were selected for this retrospective study. One eye from each patient received Toric ICL for astigmatism correction, and the other received non-astigmatic ICL surgery using horizontal position. Patients with higher postoperative arch height were selected, and their non-astigmatic eye clinical outcome were observed after ICL surgery at 1wk, 1, and 3mo. The clinical measurements included uncorrected visual acuity (UCVA), intraocular pressure (IOP), refractive state, corneal endothelium cell count, and arch height. Three months later, the ICL in each patient's non-astigmatic eye was adjusted to the vertical from the horizontal position. The results were compared before and 1wk, 1, and 3mo after adjustment.

RESULTS

UCVA and IOP were significantly reduced 1wk after position adjustment compared to 1wk after ICL implantation (P<0.05). The patients demonstrated significantly reduced arch height and corneal endothelium cell count 1wk, 1, and 3mo after adjusting position compared to 1wk, 1, and 3mo after ICL implantation (P<0.05). However, there was no significant difference in refraction between 1wk, 1, and 3mo after ICL implantation and position adjustment (P>0.05).

CONCLUSION

Early positioning adjustment post-phakic ICL implantation can benefit patients with adjusted arch height or higher IOP. Despite the good clinical effects, the doctors should pay attention to the potential for adverse effects on UCVA and corneal endothelium cells following early position adjustment after posterior chamber phakic ICL implantation.

Applications of SMILE-extracted lenticules in ophthalmology

AIM

To review recent innovations, challenges, and applications of small incision lenticule extraction (SMILE) extracted lenticule for treating ocular disorders.

METHODS

A literature review was performed in the PubMed database, which was last updated on 30 December 2021. There was no limit regarding language. The authors evaluated the reference lists of the collected papers to find any relevant research.

RESULTS

Due to the simplicity and accuracy of modern femtosecond lasers and the extensive development of SMILE surgery, many healthy human corneal stromal lenticules were extracted during surgery, motivating some professionals to investigate the SMILE lenticule reusability in different ocular disorders. In addition, new approaches had been developed to preserve, modify, and bioengineer the corneal stroma, leading to the optimal use of discarded byproducts such as lenticules from SMILE surgery. The lenticules can be effectively re-implanted into the autologous or allogenic corneas of human subjects to treat refractive errors, corneal ectasia, and corneal perforation and serve as a patch graft for glaucoma drainage devices with better cosmetic outcomes.

CONCLUSION

SMILE-extracted lenticules could be a viable alternative to human donor corneal tissue.

Changes of dry eye parameters after small incision lenticule extraction surgery in patients with different ocular surface disease index scores

To evaluate the changes of dry eye parameters after small incision lenticule extraction (SMILE) surgery in patients with different ocular surface disease index (OSDI) scores. Prospective research. Participants were divided into two groups: Group A, OSDI < 13; and Group B, OSDI ≥ 13. The OSDI scores, tear meniscus height (TMH), first non-invasive tear film break-up time (NIBUT-First), and meibomian gland loss (MGL, %) were recorded at postoperative 1 -week and 1-month.113 eyes (57 patients) were enrolled, 70 eyes in Group A, and 43 eyes in Group B. In Group A, the OSDI scores significantly increased at 1-week and 1-month postoperative (all P < 0.001); the TMH, NIBUT-First and lipid layer grade significantly decreased at postoperative 1-week (P = 0.003, 0.005, 0.007, 0.004, respectively), but returned to preoperative level at 1-month postoperative. In Group B, only the lipid layer grade significantly decreased at postoperative 1-week (P < 0.05). Patients with different preoperative OSDI scores may experience different changes early after SMILE surgery. Patients with OSDI scores < 13 may experience more dramatic changes in dry eye symptoms which would resolve, while subjective complains could still exists at 1 month after surgery.

The effect of incomplete blinking rate on corneal epithelial remodeling after trans-PRK surgery: a six-month study

Purpose

To evaluate the impact of incomplete blink rate on corneal epithelial thickness after transepithelial photorefractive keratectomy (Trans-PRK) surgery.

Methods

Trans-PRK patients were divided into two groups based on preoperative incomplete blinking rates, namely rates ≤0.5 (41 right eyes, group A) and rates >0.5 (65 right eyes, group B). We used anterior segment optical coherence tomography to measure the corneal epithelial thickness (CET) and lipiview to measure the number of blinks, incomplete blinking rate, and lipid layer thickness (LLT).

Results

In both groups, CET decreased at 1 week and 1 month, and the thicknesses in the IT, T, and ST regions exceeded the preoperative levels. Three months after Trans-PRK, the thickness exceeded the preoperative levels and continued to increase during subsequent follow-ups. The blinking times and LLT in both groups decreased at 1 week and gradually increased but did not return to preoperative levels. Group A maintained an incomplete blinking rate of over 0.5 at all postoperative periods. The incomplete blinking rate of group B remained above 0.5 postoperatively, although there was an improvement compared with preoperative rates. Both groups showed a correlation between changes in CET and incomplete blinking rate. There was a correlation between changes in LLT and the incomplete blinking rate after surgery.

Conclusion

Both groups showed uneven corneal epithelia thickening, which became more pronounced approaching the peripheral areas. In addition, changes in CET after surgery were positively correlated with the incomplete blinking rate in both patient groups. There was a negative correlation between postoperative LLT and incomplete blinking rate.

Differences in change of post-operative antioxidant levels between laser-assisted lenticule extraction and femtosecond laser in situ keratomileusis

To evaluate the change of total antioxidant capacity (TAC) and ascorbic acid (AA) between femtosecond laser in situ keratomileusis (FS-LASIK) and laser-assisted lenticule extraction (LALEX). A prospective non-randomized study was conducted, and 33 and 75 eyes that had undergone FS-LASIK or LALEX surgeries were enrolled, respectively. The tear films near corneal incisions were collected, and the concentrations of TAC and AA were determined. The generalized linear mixed model was adopted to calculate the adjusted odds ratio (aOR) with 95% confidence interval (CI) of TAC and AA between the two groups. The AA reduction was significant 1 month after the LALEX and FS-LASIK procedures (both p < 0.05), and the decrement in AA level was significantly larger in the FS-LASIK group compared to the LALEX group (p = 0.0002). In the subgroup analysis, the LALEX group demonstrated a lower decrement in TAC level in the individuals with dry eye disease (DED) than the FS-LASIK group (p = 0.0424), and the LALEX group demonstrated a significantly lower AA decrement in the participants with high myopia (p = 0.0165) and DED (p = 0.0043). The LALEX surgery causes lesser AA decrement compared to FS-LASIK surgery especially for the patients with DED.

Perioperative intense pulsed light to prevent and improve symptoms of post-laser corneal refractive surgery dry eye. A randomized clinical trial

PURPOSE

To evaluate the efficacy of perioperative IPL therapy in preventing postoperative ocular surface disorders in patients undergoing corneal laser refractive surgery.

DESIGN

randomized, controlled, clinical trial with triple-blinding.

METHODS

Setting: Vissum Miranza - Alicante; Study population: 61 patients randomized in two groups: 31 study patients (perioperative IPL + laser refractive surgery) and 30 control patients (perioperative placebo + laser refractive surgery). Follow-up was conducted over a 6-month period; Intervention: Each participants underwent three IPL sessions with a two-week interval between each session (pre-surgery, post-surgery week-one, and post-surgery week-three). For controls, placebo was administered following the same protocol.

MAIN OUTCOMES MEASURES

visual outcomes and refraction, slit-lamp examination, corneal topography, visual analogue scale questionnaire and Oculus Keratograph 5 M including tear meniscus height, non-invasive tear break- up time, ocular redness, infrared meibography and Ocular Surface Disease Index (OSDI) questionnaire.

RESULTS

61 randomized eyes were included. No significant differences were observed in terms of uncorrected and corrected distance visual acuity (UDVA, CDVA), refractive error or corneal aberrations. A statistically significant improvement in OSDI score (change -8.47, p = 0.043), tear meniscus (change 0.05 mm, p = 0.004) and Meibography (change -0.42, p = 0.012) was observed at the third postoperative month in the study group. Additionally, at the sixth postoperative month, there were statistically significant improvements in tear meniscus (change 0.06 mm, p = 0.018), tear break-up-time (change 1.68 s, p = 0.039) and Meibography (change -0.37, p = 0.030).

CONCLUSIONS

Results suggest that perioperative IPL therapy applied to laser corneal refractive surgery improves objective and subjective ocular surface parameters over non-IPL-treated control patients and early postoperative dry eye symptoms.

Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILKTM) Using the ELITA(TM) Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors

Purpose

To evaluate visual outcomes following the Smooth Incision Lenticular Keratomileusis (SILKTM) procedure for correction of myopic refractive errors with and without astigmatism, using the ELITATM Femtosecond Laser System.

Patients and Methods

A prospective, multicenter, single-arm, open-label clinical study was conducted. Eighty-five myopic subjects (n = 170 eyes), aged 18 years or older, with manifest refractive spherical equivalent (MRSE) up to -12.00 D and astigmatism up to -6.00 D, were treated binocularly using the ELITA femtosecond laser and followed up for 6 months. Intended correction was emmetropia for all eyes. The primary outcome measures included post-operative uncorrected and corrected distance visual acuity (UDVA and CDVA). Secondary outcome measures included surgeon's rating for ease of lenticule extraction, predictability, safety, and stability.

Results

A total of 170 eyes of 85 patients underwent SILK. Preoperative mean MRSE was -4.14 D ± 1.32 D (range -1.38 D to -8.88 D) and the mean cylinder was -0.77 D ± 0.62 D. Intraoperative surgeon ease of lenticule dissection was rated as grade 0 or 1 in 85.3% of eyes (no/only mild dissection needed). UDVA at 1 day, 1 week, 1 month, and 6 months was 20/20 or better in 65.9%, 85.4%, 91.5%, and 96% of eyes, respectively. No eyes lost any lines of CDVA at 6 months compared to the preoperative. The postoperative MRSE was stable over time, ranging from -0.34 D ± 0.24 D at 1 month to -0.33 D ± 0.23 D at 6 months. MRSE predictability (± 0.50 D) was 93.5% (129/138) at 3 months and 91.1% (113/124) at 6 months. No serious adverse events were noted.

Conclusion

The SILK procedure with the ELITA Femtosecond Laser System is safe and effective for the treatment of myopic refractive errors with and without astigmatism. Fast visual recovery was demonstrated, with stability achieved by 3 months.

Combination Therapy With Diquafosol Sodium and Sodium Hyaluronate in Eyes With Dry Eye Disease After Small Incision Lenticule Extraction

BACKGROUND/AIM

To evaluate the clinical efficacy of combination therapy with diquafosol sodium and sodium hyaluronate in dry eye patients after small incision lenticule extraction (SMILE).

PATIENTS AND METHODS

A prospective randomized controlled study was conducted on consecutive patients who were diagnosed with dry eye disease (DED) and ready to accept SMILE from January 2021 to December 2021. The participants were randomly allocated to either a combination with diquafosol sodium 3% and sodium hyaluronate 0.3% group (DQS group, n=40) or a sodium hyaluronate 0.3% group (HA group, n=41). Dry eye disease parameters included tear film break-up time (TBUT), Shirmer I test (SIT), corneal and conjunctival fluorescein staining score (FS score), and Ocular Surface Disease Index (OSDI); tests were conducted before surgery and at 1 week, 1 month, and 3 months after surgery.

RESULTS

At 1 week after surgery, there were no statistically significant overall differences in DED parameters between the 2 groups. At postoperative month 1, the FS score was significantly lower in the DQS group than in the HA group (1.20±1.06 vs. 1.83±1.41 respectively, p=0.026). At 3 months after the surgery, the DQS group was significantly superior to the HA group in OSDI (12.98±7.29 vs. 16.82±8.25, p=0.029), TBUT (5.83±2.02 vs. 4.24±0.94, p=0.0002), and SIT (7.75±3.92 vs. 5.24±3.42, p=0.003).

CONCLUSION

Our study showed that combination therapy with diquafosol and hyaluronate was beneficial for improving both signs and symptoms of dry eye patients after small incision lenticule extraction.

Effect of 3% Diquafosol Sodium on Dry Eye After Femtosecond Laser-Assisted In Situ Keratomileusis and Small Incision Lenticule Extraction Surgery in High-Myopic Eyes

PURPOSE

To evaluate the effect of 3% diquafosol sodium eye drop on dry eye after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) in high-myopic eyes.

METHODS

Eighty-one cases with high myopia (162 eyes) who received FS-LASIK or SMILE were divided into four groups by surgical design and tear film stability: D-FS-LASIK (5s

RESULTS

The D-SMILE group showed increase in BUT postoperatively (1m: P =0.006, 3m: P =0.004), whereas C-FS-LASIK (1m: P =0.012) and C-SMILE (1m: P =0.036) groups showed decrease in BUT. Higher ΔBUT were observed in D-FS-LASIK (1m: P =0.027) and D-SMILE (1m: P =0.001, 3m: P =0.012) postoperatively. The D-FS-LASIK group showed less decrease than C-FS-LASIK group in Schirmer I. The D-SMILE group showed increase in Schirmer I, whereas C-SMILE showed decrease in 3 months. ΔOSDI was lower in D-SMILE group than in C-SMILE group (1m: P =0.026, 3m: P =0.035). Fatigue was severer in D-SMILE group than in C-SMILE group preoperatively ( P =0.019), although there was no significant difference postoperatively. Objective scattering index (1m: P =0.002, 3m: P =0.021) and tear film objective scattering index (1m: P =0.005, 3m: P =0.010) were lower in D-FS-LASIK group than in C-FS-LASIK group postoperatively. The D-FS-LASIK group showed better VA20% ( P =0.036) and VA9% ( P =0.027) than the C-FS-LASIK group 1 month postoperatively.

CONCLUSIONS

3% Diquafosol sodium eye drop was effective for SMILE and FS-LASIK-related dry eye in high-myopic eyes. It is necessary to focus on perioperative anti-dry eye management and especially pay attention to the eyes with risk factors, including unstable tear film, high myopia, and FS-LASIK surgery.

Collapse

Key Words Collapse

MESH Headings

• Humans
• Keratomileusis, Laser In Situ/adverse effects
• Hyaluronic Acid/therapeutic use
• Myopia/etiology
• Dry Eye Syndromes/drug therapy
• Dry Eye Syndromes/etiology
• Dry Eye Syndromes/surgery
• Lasers, Excimer/therapeutic use
• Ophthalmic Solutions
• Corneal Stroma/surgery

Collapse

Grants

• No. Z201100005520043 Beijing Municipal Science and Technology Commission

Collapse

Affiliation(s)

Dengxin Gao Beijing Ophthalmology and Visual Science Key Lab, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
Xiaotong Lv
Fengju Zhang
Yanzheng Song
Yushan Xu

Collapse

Femtosecond-laser-assisted Small Incision Lenticule Extraction to Treat Refractive Error: A Narrative Review

With the approval of the Federal Drug Agency of the USA in 2018, femtosecond laser-assisted small incision lenticule extraction (SMILE) became an officially available option in several countries including Saudi Arabia to treat myopia and astigmatism. Intense marketing by industries has placed both clients and corneal surgeons into a dilemma of the plus and minuses of this option. Although several reviews compare SMILE to other conventional methods, especially laser in situ keratomileusis, this narrative review perhaps for the first time offers a detailed summary of this procedure and compares two sets of published literature, by authors from China and other countries. The efficacy and safety of SMILE seem to outnumber the complications and high cost of the investment. Its long-term usefulness for treating high myopia and hyperopia is still a matter of research.

Changes of Subjective Symptoms and Tear Film Biomarkers Following Lenticule Extraction

PURPOSE

To investigate the influence of lenticule extraction on subjective symptoms and objective biomarkers of dry eye and to clarify relationships between markers and find indicators for subjective symptoms after lenticule extraction.

METHODS

Right eyes of myopic patients undergoing lenticule extraction surgery (n = 35) were examined preoperatively and 5 and 90 days postoperatively using established clinical dry eye examination methods (tear film break-up time [BUT], Schirmer test, lissamine green and fluorescein staining, and Ocular Surface Disease Index (OSDI) questionnaire). A patient subset was also examined after 1 year (n = 14). Tear samples were eluted from Schirmer strips and then measured with enzyme-linked immunosorbent assays (calcitonin gene-related peptide (CGRP), interleukin-1β, IL-6, IL-8, matrix metallopeptidase 9 [MMP-9], nerve growth factor, and tumor necrosis factor-α). Postoperatively, unpreserved ofloxacin and dexamethasone eye drops were given (four times a day for 10 days).

RESULTS

BUT decreased at days 5 (P = .023) and 90 (P = .025). Lissamine green staining increased at day 90 (P = .036). OSDI values increased at day 5 (total values, vision-related function, ocular symptoms, all P < .001, but not environmental triggers) and at day 90 (vision-related function, P = .017). A downregulation of CGRP (P = .006) and MMP-9 levels (P = .042) was observed on day 5 compared to day 90.

CONCLUSIONS

Due to incongruity of patient symptoms, clinical signs, and tear protein changes, no predictive indicator was found, but some patients reported increased discomfort. Changes after lenticule extraction are not exclusively due to dry eye. [J Refract Surg. 2023;39(9):597-604.].

Patient-Reported Dry Eye Outcomes After Myopic Femtosecond-LASIK: A 6-Month Prospective Analysis

Purpose

To evaluate patient-reported outcomes in relation to dry eye symptoms following femtosecond LASIK (FS-LASIK).

Methods

This study was conducted as a prospective, observational case series of patients undergoing bilateral myopic FS-LASIK at a single private practice institution. Enrolled patients were prospectively administered a standardized Dry Eye Symptom Index survey (analog score of 1 to 5 with 5 being the worst) prior to treatment and at 6-months after FS-LASIK. The following objective measurements were also recorded: objective scatter index (OSI), tear film osmolarity (TFO), and automated tear break-up times (TBUT).

Results

There were 40 enrolled patients who underwent bilateral myopic FS-LASIK and completed the 6-month study period. The Dry Eye Symptom Index score improved from 2.3 (2.0-2.6, 95% Confidence Intervals) prior to treatment to 1.3 (1.0-1.5) at 6 months (p < 0.0001). Subset analysis of the subjective dry eye symptoms showed improvement in "grittiness" (p = 0.001) but not in "light sensitivity" or "soreness" (p = 0.13 and p = 0.24, respectively). There were no significant changes in the OSI, TFO, or TBUT measurements at 6 months (p > 0.05 for all), and there were no adverse events or complications during the study period.

Conclusion

Patient-reported dry eye symptoms improve after 6 months following myopic FS-LASIK. This did not correlate with the objective dry eye measurement changes at 6 months.

Evaluation of lipid layer tear film changes after femtosecond small incision lenticule extraction

Background:

Dry eye disease is common after refractive procedures due to tear film instability. There are several causative factors for tear film instability, but the state of individual components of the tear film is not assessed much in published literature. This article quantifies the lipid layer thickness (LLT) of the tear film using surface interferometry before and after the small incision lenticule extraction (SMILE) refractive procedure.

Objectives:

This study aimed to evaluate the effects of femtosecond SMILE on the postoperative stability of the LLT of the tear film.

Design:

This was a prospective, interventional, non-case–control study.

Methods:

A total of 160 eyes of 80 patients were enrolled in the study. The follow-up period was 6 months after surgery. A noninvasive surface interferometer was used to measure the thickness of the lipid layer before surgery and was repeated at 3 and 6 months after surgery. The main outcome measure was the change in average LLT at 3 and 6 months after SMILE and its statistical significance.

Results:

There were 48 women and 32 men. Age ranged from 21 to 42 years (mean = 27 ± 6.4). Mean LLT at baseline was [oculus dextrus (OD) = 53.38 (±7.24) nm; oculus sinister (OS) = 52.21 (±6.95) nm], at 3 months [OD = 54.38 (±5.75) nm; OS = 53.26 (±5.70)], and at 6 months [OD = 53.31 (±5.66) nm; OS = 52.39 (±5.94)]. Mean LLT showed mild improvement at 3 months after surgery (OD = 53.38–54.38 mm, p = 0.0417; OS = 52.21–53.26 mm, p = 0.0398). There was no significant change in LLT from the baseline before surgery to levels 6 months after surgery (p = 0.8914 OD; p = 0.7368 OS).

Conclusion:

The SMILE refractive procedure did not alter the LLT that remained stable and adequate at 6 months postoperative follow-up.

Small incision lenticule extraction (SMILE) refractive surgery: Our initial experience

Background

Small incision lenticule extraction (SMILE) is femtosecond laser based, minimally invasive, flap-free refractive surgery gaining worldwide acceptance as a safe alternative to flap based refractive surgeries.

Methods

A retrospective data review study was done where preoperative and postoperative data were collected for 202 eyes of 101 patients who underwent SMILE surgery at a tertiary care Armed Forces hospital from Jan 2019 to Dec 2019. All participants included in the study were followed up for 3 months postoperative period.

Results

Mean age of the participants was 24.139 ± 0.515 years (males 22.1 years, females 25.3 years). Male participants were 36 (72 eyes) while female participants were 65 (130 eyes). Of the participants, 75.2% underwent the procedure for cosmetic indication, while 24.8% underwent clearing some medical examination later. Preoperative UCVA was 1.049 ± 0.028 logMAR units, which improved on first postoperative day to 0.038 ± 0.01 logMAR units, at 1 wk 0.015 ± 0.01 logMAR units, at 1 month 0.006 ± 0.005 logMAR units and at 3 months postoperative period to 0.03 ± 0.003 logMAR units. There were two adverse events of difficult lenticule extraction with small (<1 mm) cap tear.

Conclusion

SMILE surgery is a flap-free refractive surgical technique. It reduces postoperative complications like dry eyes and flap-related complications. Hence, it may be recommended for all serving personnel after a thorough preoperative screening protocol.

Understanding chronic ocular surface pain: An unmet need for targeted drug therapy

Chronic ocular surface pain (COSP) may be defined as a feeling of pain, perceived as originating from the ocular surface, that persists for >3 months. COSP is a complex multifactorial condition associated with several risk factors that may significantly interfere with an individual's daily activities, resulting in poor quality of life (QoL). COSP is also likely to have a high burden on patients with substantial implications on global healthcare costs. While patients may use varied terminology to describe symptoms of COSP, any ocular surface damage in the ocular sensory apparatus (nociceptive, neuropathic, inflammatory, or combination thereof) resulting in low tear production, chronic inflammation, or nerve abnormalities (functional and/or morphological), is typically associated with COSP. Considering the heterogeneity of this condition, it is highly recommended that advanced multimodal diagnostic tools are utilized to help discern the nociceptive and neuropathic pain pathways in order to provide targeted treatment and effective clinical management. The current article provides an overview of COSP, including its multifactorial pathophysiology, etiology, prevalence, clinical presentation, impact on QoL, diagnosis, current management, and unmet medical needs.

Dry eye syndrome: comprehensive etiologies and recent clinical trials

Dry eye syndrome (DES) is multifactorial and likely to be a cause of concern more so than ever given the rapid pace of modernization, which is directly associated with many of the extrinsic causative factors. Additionally, recent studies have also postulated novel etiologies that may provide the basis for alternative treatment methods clinically. Such insights are especially important given that current approaches to tackle DES remains suboptimal. This review will primarily cover a comprehensive list of causes that lead to DES, summarize all the upcoming and ongoing clinical trials that focuses on treating this disease as well as discuss future potential treatments that can improve inclusivity.

Femtosecond Small Incision Lenticular Extraction in comparison to Femtosecond Laser In situ Keratomileusis Regarding Dry Eye Disease

 Abstract Objective: Comparison of femtosecond small incision lenticule extraction (FS-SMILE) versus Femtosecond laser Insitu keratomileusis (FS-LASIK) regarding dry eye disease (DED) and corneal sensitivity (CS) after those refractive surgeries. Methods: A comparative prospective study conducted for a period of 2 years; from March 2017 until February, 2019. Enrolled patients were diagnosed with myopia. Fifty patients (100 eyes) were scheduled for bilateral FS-SMILE and the other 50 patients (100 eyes) had been scheduled for bilateral FS-LASIK. Both groups were followed for six months after surgery. The age, gender, and preoperative refraction for both groups were matched. Complete evaluation of dry eye disease had been performed for the intervals of one week pre-operatively, one and six months postoperatively. The evaluation included history of symptoms according to scoring systems, investigations and clinical examination. Results: One month postoperatively and in both groups, there was significant DED (P < .01), although the incidence was lower in femtosecond SMILE group, overall severity score (0-4): 0.3 ± 0.3 (FS-SMILE) vs. 1.4 ± 0.9 (LASIK). One month postoperatively, CS was lower in FS- LASIK more than FS-SMILE eyes (2.3 ± 2.2 vs 3.6 ± 1.8, respectively, P < .01) and then return to not statistically significant sensitivities at six-month duration. DED was negatively correlated with CS (P < 0.01). Conclusions: The FS-LASIK surgery had a more pronounced effect on the CS and DED compared with FS-SMILE, with higher incidence of DED postrefractive surgery.

Assessment and Management of Dry Eye Disease and Meibomian Gland Dysfunction: Providing a Singapore Framework

ABSTRACT

The purpose of this article is to provide a framework for general ophthalmologists in Singapore to manage dry eye. This framework considers the evidence in the literature as well as recommendations from expert panels such as the Tear Film & Ocular Surface Society Dry Eye Workshop II and the Asia Cornea Society Workgroup.This article covers the assessment of patient medical history and ask triage questions to identify local and systemic causes of dry eye disease (DED), excluding other possible causes, as well as the risk factors for DED and ocular surface inflammation. Evaluation of clinical signs to establish the diagnosis of DED and differentiation from other causes of irritable, red eyes are described. Tests for understanding the underlying disease processes and severity of DED are also presented.Management of dry eye should involve patient education and engagement. Information about the natural history and chronic nature of DED should be provided to improve long-term management of the disease and enhance compliance. Aggravating factors should be removed or lessened.We provide a guide to determine the most appropriate treatment (or combination of treatments) based on the severity and cause(s) of the disease, as well as the patient's needs and preferences. The aim of the management is to relieve ocular discomfort and prevent worsening of symptoms and signs, as well as to optimize visual function and minimize structural ocular damage. We also discuss the systematic follow-up and assessment of treatment response, as well as monitoring side effects of treatment, bearing in mind continuous support and reassurance to patients.

Impact of extreme (flat and steep) keratometry on the safety and efficacy of small incision lenticule extraction (SMILE)

Little is known about the connection between preoperative keratometry and postoperative results of myopic small-incision lenticule extraction (SMILE). To determine the influence of extreme (flat and steep) corneal keratometry on the safety and efficacy of SMILE, the databases of the Department of Ophthalmology, Ludwig-Maximilians-University Munich, Germany, and SMILE Eyes Linz, Austria, were screened for patients with steep and flat keratometry who had undergone SMILE. In this cross-sectional matched comparative cohort study, eyes with markedly flat (< 42.0 diopters; D) or steep (≥ 47.0D) preoperative corneal keratometry were matched to a cohort of eyes with regular keratometry (42.0-46.9D) by preoperative manifest refractive spherical equivalent and cylinder, age, corrected distance visual acuity and surgical SMILE parameters. The standardized graphs and terms for refractive surgery results were applied to compare the three groups. Changes in higher order aberrations (HOAs) were evaluated on Scheimpflug imaging. In total, 63 eyes (21 each) of 54 patients with a mean refractive spherical equivalent of  - 5.21 ± 1.59 D were followed up for a mean of 9.2 ± 6.1 (minimum ≥ 3) months. Mean baseline keratometry was 41.3 ± 0.7D (flat), 45.5 ± 1.0D (regular) and 47.7 ± 0.6D (steep) (p < 0.0001). Compared to the regular group, the flat and the steep cornea group resulted in a non-inferior percentage of eyes within ± 0.50 D of target refraction (p = 0.20), uncorrected distance visual acuity (p = 0.95) and corrected distance visual acuity (p = 0.20). Flat corneas however experienced a stronger induction of spherical aberration (SA) compared to the steep group (p = 0.0005). In conclusion, non-inferior outcomes of SMILE can also be expected in eyes with steep (≥ 47D) or flat (< 42D) preoperative keratometry, while SMILE however induces more SA in eyes with a flat keratometry.

Options and results in managing suction loss during small-incision lenticule extraction

Suction loss is an intraoperative complication in small-incision lenticule extraction (SMILE) that presents a management challenge for the refractive surgeon. The purpose of this review is to evaluate the visual, refractive, and wavefront outcomes after suction loss across the different stages of SMILE with various respective surgical treatments. Surgical management options include immediate re-SMILE by redocking or delayed re-SMILE, with or without adjustment of the laser parameters, conversion to femtosecond laser in situ keratomileusis, transepithelial photorefractive keratectomy, refractive lenticule extraction, or pseudo-SMILE. The restart treatment module on VisuMax provides appropriate retreatment recommendation. Most retreatment options for suction loss, immediate or delayed, resulted in effective, safe, and predictable outcomes, and patients were satisfied with their outcomes. Based on available level II evidence, immediate re-SMILE with or without adjustment to the laser settings achieve favorable visual and refractive outcomes in handling this intraoperative complication across all stages of SMILE.

Feasibility, Safety, and Outcomes With Standard Versus Differential Spot Distance Protocols in Eyes Undergoing SMILE for Myopia and Myopic Astigmatism

PURPOSE

To study the feasibility, safety, comparison of intraoperative ease of dissection, and immediate visual outcomes with standard versus differential small incision lenticule extraction (SMILE) spot settings in eyes undergoing bilateral SMILE for myopia or myopic astigmatism.

METHODS

One hundred eyes of 50 patients (mean age: 25.4 years) were randomized to receive standard settings (4.5-µm spot and track spacing in cap and lenticule interface) in one eye and differential settings (4.5-µm spot and track spacing in cap interface and 4.2 µm in lenticule interface) in the contralateral eye. Opaque bubble layer (OBL) was graded using a new grading system and a surgeon questionnaire was obtained to grade the ease of dissection (from 0 to 5, with 5 being the easiest) at the end of each surgery. Visual results and optical quality were analyzed at 1 day, 2 weeks, and 3 months postoperatively.

RESULTS

The mean OBL score was significantly lower in the differential group (26.3%) compared to the standard group (35.3%) (P < .01). Consequently, the mean dissection score was significantly higher in the differential group (4.01) compared to the standard group (3.57) (P < .01). The uncorrected distance visual acuity, Objective Scatter Index, modulation transfer function cut-off, and higher order aberrations were comparable with no statistically significant difference between both groups at 1 day, 2 weeks, and 3 months postoperatively (P > .05 for all parameters). No eye in either group had any intraoperative or postoperative complication affecting visual recovery.

CONCLUSIONS

Differential spot settings resulted in less intraoperative OBL and easy separability. However, the visual results and optical quality were comparable between groups. [J Refract Surg. 2021;37(5):294-302.].

Advances in refractive corneal lenticule extraction

Refractive errors are the leading cause of reversible visual impairment worldwide. In addition to the desired spectacle independence, refractive procedures can improve quality of life, working ability, and daily working performance. Refractive corneal lenticule extraction (RCLE) is a relatively new technique, dependent only on a femtosecond laser (FS). This leads to potential benefits over laser-assisted in situ keratomileusis (LASIK) including a quicker recovery of dry eye disease, a larger functional optical zone, and no flap-related complications. SMILE, available with the VisuMax FS (Carl Zeiss Meditec AG, Jena, Germany), is the most established RCLE application, offering visual and refractive outcomes comparable to LASIK. SmartSight (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany) and CLEAR (Ziemer Ophthalmic Systems AG, Port, Switzerland) are two new RCLE applications that received Conformité Européenne (CE) approval in 2020. In this article, we review refractive and visual outcomes, advantages, and disadvantages of RCLE and also report on the latest advances in RCLE systems.

Small Incision Lenticule Extraction (SMILE): Myths and Realities

The emergence of SMILE in the last decade has provided an alternative to LASIK for patients considering cornea laser refractive surgery. SMILE offers a novel approach using the femtosecond laser to create an intrastromal lenticule that can be removed through a small three to four millimeter incision.The purpose of this study is to review the recent literature on popular SMILE claims - reduced iatrogenic dry eye, better recovery of corneal sensation, and a biomechanically stronger cornea - summarize the published outcomes, and determine which claims are myths versus realities.SMILE is still in its infancy as a refractive technique in the US after recent USFDA approval for its treatment of myopia astigmatism in October 2018. Future randomized controlled studies are needed to compare its outcomes to LASIK, which has well-documented good visual outcomes, rapid postoperative recovery, and good safety profile.

Silk Film Stiffness Modulates Corneal Epithelial Cell Mechanosignaling

Silk fibroin films are excellent candidate biomaterials for corneal tissue engineering due to their optical transparency, biocompatibility, and mechanical strength. Their tunable chemical and mechanical properties open the possibility of engineering cellular microenvironments that can both mimic native corneal tissue and provide stimuli to actively promote wound regeneration. While silk film mechanical properties, such as surface topography, have demonstrated the ability to control corneal epithelial cell wound regenerating behavior, few studies have explored the stiffness tunability of these films and its cellular effects. Cells are known actively sense the stiffness of their surroundings and processes such as cell adhesion, migration, proliferation, and expression of stem markers can be strongly influenced by matrix stiffness. This study develops technical solutions that allow for both the fabrication of films with stiffnesses similar to corneal tissue and also for their characterization in an aqueous, native-like environment at a scale relevant to cellular forces. Physiological evidence demonstrates that corneal epithelial cells are mechanosensitive to films of different stiffnesses and show that cell spreading, cytoskeletal tension, and molecular mechanotransducer localization are associated with film stiffness. These results indicate that silk film stiffness can be used to regulate cell behavior for the purposes of ocular surface repair.

SMILE Versus Implantable Collamer Lens Implantation for High Myopia: A Matched Comparative Study

PURPOSE

To compare the safety, efficacy, and patient-reported quality of vision of small incision lenticule extraction (SMILE) and implantable Collamer lens (ICL) implantation for the treatment of high myopia.

METHODS

A database of 1,634 SMILE (Carl Zeiss Meditec AG, Jena, Germany) and 225 ICL implantation (STAAR Surgical, Monrovia, CA) procedures was screened for patients with a binocular preoperative manifest refraction spherical equivalent between -6.00 and -10.00 diopters (D) and plano target refraction. One-to-one matching was performed by preoperative manifest refraction spherical equivalent, age, and pupil size. All identified patients were then prospectively examined at their next regular postoperative follow-up visit and presented with the standardized and clinically validated Quality of Vision questionnaire to gauge patient-reported postoperative visual quality.

RESULTS

A total of 80 eyes (40 patients) were eligible for 1:1 matching. Mean postoperative follow-up was 27.8 ± 14.3 months in the SMILE group and 26.6 ± 17.7 months in the ICL group (P = .44). Regarding the percentage of eyes within ±0.50 D of plano target, refractive predictability was better in eyes treated with ICL implantation (90%) than SMILE (72.5%) (P = .045). Mean UDVA was comparable (ICL: -0.09 ± 0.10 logMAR; SMILE: -0.06 ± 0.09 logMAR; P < .09), but the efficacy (1.28 vs 1.05; P < .001) and safety (1.31 ± 0.22 vs 1.10 ± 0.25; P < .001) indices were higher after ICL implantation. ICL implantation induced significantly fewer higher order aberrations (total higher order aberrations: SMILE 0.724 ± 0.174 µm vs ICL 0.436 ± 0.114 µm; P < .01). Regarding subjective quality of vision, patients who had ICL implantation were significantly less bothered by visual disturbances, which were mainly halos after ICL and starbursts and fluctuations of vision after SMILE (P < .05).

CONCLUSIONS

In this refraction-matched comparative study, ICL implantation for high myopia yielded better refractive accuracy, better uncorrected distance visual acuity, fewer higher order aberrations, and better subjective quality of vision than SMILE. [J Refract Surg. 2020;36(3):150-159.].

Impact of corneal refractive surgery on the precorneal tear film

Corneal refractive surgeries are one of the commonly performed procedures for correction of refractive errors. Tear film abnormality is the most common postoperative complication of corneal refractive surgeries. Consequently, these procedures represent a clinically significant cause of dry eye disease. The mechanisms which lead to dry eye disease include corneal sensory nerve dysfunction, ocular surface desiccation, glandular apoptosis and ocular surface inflammation. Although transient tear film abnormalities occur in almost all patients following surgery, patients with pre-existing dry eye symptoms or dry eye disease are at significant risk of developing more severe or long-term ocular surface disease. As such, careful patient selection and preoperative evaluation is essential to ensuring successful surgical outcomes. This is particularly important with LASIK which has the strongest association with dry eye disease. Appropriate surface lubrication and anti-inflammatory therapy remains the cornerstone treatment. Timely and effective management is important to facilitate visual rehabilitation and reduce the risk of secondary complications. In this review we describe the causes, pathophysiology, risk factors, manifestations, and management of tear film dysfunction and dry eye disease following corneal refractive surgery.

A Review on Different Tonometers for Intraocular Pressure Measurement After Photorefractive Keratectomy or Small Incision Lenticule Extraction

This paper aims to review different tonometers for intraocular pressure measurement in eyes after photorefractive keratectomy or small incision lenticule extraction. An Entrez Pubmed search was performed on July 19th, 2020. There were 32 eligible articles investigated in the use of tonometers or biomechanical properties of cornea in post photorefractive keratectomy eyes and 11 articles investigated in post small incision lenticule extraction eyes. Corvis ST and dynamic contour tonometry were found to be accurate for intraocular pressure measurement in post photorefractive keratectomy eyes. For post small incision lenticule extraction eyes, Corvis ST was found to be more accurate than other tonometers. Other tonometers such as Goldmann applanation tonometer, noncontact tonometry, Tonopen, ocular response analyzer can also be used in post photorefractive keratectomy or small incision lenticule extraction eyes in clinical practice; however, it is important for ophthalmologists to take note of the chances of discrepancies.