Management of the Ocular Surface and Tear Film Before, During, and After Laser in situ Keratomileusis

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.

Incidence and Management of Epithelial-Related Complications After SMILE

Purpose

To investigate the incidence and management of only epithelial-related complications following small incision lenticule extraction (SMILE).

Patients and Methods

A retrospective, single-site study analyzed patients who underwent SMILE at Hoopes Vision Clinic in Draper, Utah, from June 2017 to February 2023. Demographic data and preoperative parameters were reviewed. Postoperatively, patients were assessed for visual acuity and complications at different time points. Statistical analyses were conducted between the control and complication groups.

Results

Four hundred and thirty-two eyes of 220 patients received SMILE. Postoperative epithelial-related complications were indicated in 68 (15.7%) eyes, including anterior basement membrane (ABM) changes (five [1.2%]) eyes), epithelial ingrowth (nine [2.1%] eyes), erosion (two [0.5%] eyes), rough epithelium (18 [4.2%] eyes), epithelial defect (12 [2.8%] eyes), diffuse lamellar keratitis (DLK) secondary to epitheliopathy (two [0.5%] eyes), microstriae secondary to epitheliopathy (four [0.9%] eyes), interface debris (21 [4.9%] eyes), and incisional fibrosis (one [0.2%] eye). There was a statistically significant difference in age, with older patients more likely to develop epitheliopathy postoperatively (P = 0.001). Additionally, patients with epithelial-related complications were more likely to receive photorefractive keratectomy (PRK) enhancement after SMILE than the control (P = 0.001). However, there was no statistical difference in uncorrected distance visual acuity (UDVA) better than 20/20 and corrected distance visual acuity (CDVA) between the complications group and the control at the last postoperative visit (P = 0.974 and 0.310, respectively). There was no statistically significant difference in the safety and efficacy indices between the complications and control group (P = 0.281 and 0.617, respectively).

Conclusion

In our study, epithelial-related complications were more prevalent in older patients and predisposed patients to require PRK enhancements after recovery from SMILE. Despite the incidence of epithelial-related complications, visual prognoses were favorable and achieved through various management strategies.

Evaluation of Dry Eye After Refractive Surgery According to Preoperative Meibomian Gland Status

Purpose

To investigate the effect of the preoperative meibomian gland (MG) status on dry eye symptoms after corneal refractive surgery.

Methods

This is a prospective, observational study. Subjects were enrolled and classified into 3 groups according to their MG loss grades. Ocular surface parameters were measured preoperatively and at 1, 3, and 6 months, postoperatively, including the ocular surface disease index questionnaire (OSDI), non-invasive tear film break up time (NIBUT), tear meniscus height and Schirmer I test. All the parameters were analyzed among the three groups, and different time points.

Results

Seventy-eight patients were included in this study. The grade of MG loss varied from 0 to 2, thus the subjects were divided into group 1–3 corresponding to the MG loss. There were no significant differences in all parameters at baseline. The OSDI score increased in all groups at 1 month postoperatively and then decreased after other follow-ups. The OSDI was higher in group 3 than group 1 at all time points postoperatively (P = 0.005, 0.002, 0.034). Besides, it was higher in group 2 at 3 months and 6 months, compared with group 1 (P = 0.006, 0.029). The average NIBUT was shorter in group 3, compared with group 1 and group 2 since 1 month after surgery. At 1 and 3 month postoperatively, the grade of MG loss was positively correlated with the total OSDI and the vision-related scores. And it showed a positive correlation only with the environmental score at 6 months postoperatively.

Conclusions

The dry eye discomfortable symptoms significantly differed post operatively according to their preoperative MG loss grade, though no difference was found at baseline. Dry eye was associated more with vision-related discomfort at first and environmental factors later.

Characteristics of Toxic Keratopathy, an In Vivo Confocal Microscopy Study

Purpose

Toxic keratopathy (TK) involves complex clinical manifestations and is difficult to differentiate from other ocular surface diseases by conventional slit-lamp examination. The challenge faced by clinicians in confidently diagnosing TK cannot be underestimated. This study aimed to explore the microstructural characteristics and diagnostic parameters by in vivo confocal microscopy (IVCM) in TK.

Methods

In this prospective, cross-sectional, comparative study, slit-lamp and IVCM examinations were performed on 20 normal eyes and 54 eyes with TK. Based on slit-lamp imaging, TK subjects were divided into four groups: superficial punctate keratitis (n = 10 eyes), pseudodendritic keratitis (n = 14 eyes), ulcerative keratitis (UK; n = 16 eyes), and ring keratitis (RK; n = 14 eyes). The microstructural characteristics of TK were described according to the following IVCM parameters: basal cell (BC) density, dendritiform cell (DC) density, DC size, corneal nerve fiber (CNF) length, nerve tortuosity, and keratocyte reflectivity. A receiver operating characteristic (ROC) curve model was also formulated to compare the predictive power of BC density, DC density, and CNF length.

Results

TK eyes showed significantly higher values for DC density (45.8 cells/mm²; range, 25.0–100.0) compared with normal eyes (24.0 cells/mm²; range, 20.8–32.3; P = 0.013; DC size (111.0 µm²; range, 92.0–137.8) compared with normal eyes (63.7 µm²; range, 47.7–70.3; P < 0.001); nerve tortuosity (0.08; range, 0.05–0.09) compared with normal eyes (0.04; range, 0.02–0.04; P < 0.001); and keratocyte reflectivity. BC density and CNF length values were found to be significantly less than those for normal controls (both P < 0.001). In all subgroups, CNF length appeared to be significantly lower than that of controls (all P < 0.001), and DC density was only statistically significantly higher in the UK (P = 0.003) and RK (P < 0.001) groups. Corneal fluorescein staining had no correlation with the analyzed IVCM parameters (all P ˃ 0.05). However, the increase in DC density and DC size showed negative correlations to CNF length (density: r = −0.325, P < 0.005; size: r = −0.493, P < 0.005), as well as positive correlations to duration and frequency of topical eye drops and DC size (density: r = 0.361, P < 0.05; size: r = 0.581, P < 0.05). A ROC curve showed that CNF length had the strongest predictive power, with the estimated area under the curve being 0.992 ± 0.008.

Conclusions

Lower BC density and CNF length, greater DC density and DC size, and greater keratocyte reflectivity were the microstructural characteristics of TK. The role of subbasal nerve, inflammatory response, and limbal stem cells in the progression of TK and the appropriate treatment of different TK stages are future research directions.

Translational Relevance

The evaluation of basal cells, subbasal nerve, and dendritiform cells is helpful to our understanding of the pathological process of TK.

Changes in Tear Osmolarity after Cataract Surgery

BACKGROUND

The purpose of this study was to examine changes in the ocular surface before and after phacoemulsification with small incisions and to examine the changes in tear osmolarity.

METHODS

This was a prospective, observational study involving 55 eyes of 39 patients (19 male, 20 female patients; average age 72.0±7.3 years) who had cataract surgery at a Nippon Medical School Hospital between December 2013 and June 2018. Compromised tear dynamics were determined by the Schirmer test or the tear break-up time (BUT). An abnormal ocular surface was identified by positive vital staining with fluorescein or lissamine green. Moreover, tear osmolarity (Tosm) and corneal sensitivity were measured. All assessments were done preoperatively and 1 and 4 weeks (P1W and P4W) after the surgery.

RESULTS

None of the operations had any complications. Operating time was 17.8±9.3 minutes. BUT was significantly decreased at P1W, and it recovered at P4W. The Schirmer test did not change significantly. The fluorescein staining score (FSS) increased significantly at P1W and recovered at P4W. The Lissamine green score (LSS) did not change significantly. Tear osmolarity increased significantly at P1W and did not recover at P4W. Corneal sensitivity decreased significantly at P1W and recovered at P4W.

CONCLUSION

In the present study, there were temporary changes in dry eye-related examinations including tear osmolarity after cataract surgery. In particular, tear osmolarity increased significantly 4 weeks after surgery compared to before surgery, and it showed long-term changes, unlike other factors. After cataract surgery, tear osmolarity, BUT, and FSS increase, resulting in dry eye symptoms. Therefore, it is necessary to pay attention to discomfortable eye symptoms of patients after cataract surgery.

Intense Pulse Light for Treating Post-LASIK Refractory Dry Eye

Objective: Optimal pulse technology-intense pulse light (OPT-IPL) treatment on patients with post-LASIK refractory dry eye (DE). Background: The prevalence of dry eye disease is common and can lead to ocular discomfort, reduced visual acuity, lowered quality of vision and life. Materials and methods: A prospective study was conducted on 72 eyes of 36 patients (treatment group, n = 42 eyes; control group, n = 30 eyes) who had previously undergone myopic LASIK correction with subsequent refractory DE. All eyes fulfilled the Japanese DE criteria and had not responded to conventional DE treatment. The treatment group underwent two OPT-IPL treatment sessions at 2-week intervals, while the control group received no treatment. Best-corrected visual acuity (BCVA), ocular surface disease index (OSDI), noninvasive breakup time (NITBUT), tear film lipid layer (TFLL) quality, corneal fluorescein staining, meibum gland (MG), endothelial cell count (ECC), and intraocular pressure (IOP) were assessed at baseline (D0), day-14 (D14) and day-28 (D28) after OPT-IPL treatment. Results: The mean age of treatment group and control group was 30.48 ± 5.16 years (12 females, 57%) and 31.00 ± 4.33 years (8 females, 53%), respectively. Treatment group had clinically and statistically significant improvement in NITBUT and was observed at D14 (p < 0.001) and D28 (p < 0.001). OSDI, TFLL score, and MG quality and expressibility improved significantly (p < 0.05) at D28, whereas BCVA, ECC, and IOP showed no significant changes at D14 and D28 between the groups. Conclusions: Our results suggest that post-LASIK refractory DE is safely treated with OPT-IPL treatment. OPT-IPL treatment reduced the severity of symptoms and improved the overall tear film stability in patients with severe refractory DE post-LASIK surgery. In addition, the frequency of artificial tears usage was significantly less and can be attributed to the reduction in OSDI scores due to improved TFLL and tear film stability.

Assessment of meibomian glands and tear film in post-refractive surgery patients

IMPORTANCE

Corneal refractive surgery may impact meibomian gland and tear film in post-refractive surgery patients.

BACKGROUND

To compare ocular surface parameters between post-refractive surgery patients and normal controls.

DESIGN

Cross-sectional single centre study.

PARTICIPANTS

A total of 120 eyes of 120 subjects were divided into three groups: (i) 60 controls and 60 patients underwent corneal refractive surgery at least 12 months ago; (ii) 30 post-laser in-situ keratomileusis (LASIK) patients and (iii) 30 post-laser epithelial keratomileusis (LASEK)/photo-refractive keratectomy (PRK) patients.

METHODS

Tear meniscus height, non-invasive keratographic tear film break-up time and meibography were measured using the Keratograph^® 5M. Fluorescein break-up time, ocular surface staining, examination of lid margins and meibomian glands, Schirmer's test and Ocular Surface Disease Index questionnaire were performed.

MAIN OUTCOME MEASURES

Ordinary logistic regression was performed to evaluate the impact of clinical variables including refractive surgery on the meiboscores.

RESULTS

In post-LASIK patients, ocular surface parameters including Ocular Surface Disease Index scores, fluorescein break-up time and staining scores, except Schirmer's scores, were significantly worse than those in controls (P < 0.050). Ocular surface staining scores in post-LASEK/PRK patients was higher than that in the controls (P = 0.001). In post-refractive surgery patients, grade of meibomian gland parameters and meiboscores were worse than those of controls (all P < 0.050). Histories of refractive surgery were associated with high meiboscore (β = 1.100, P = 0.043 for LASIK and β = 1.039, P = 0.042 for LASEK/PRK).

CONCLUSIONS AND RELEVANCE

Corneal refractive surgery may adversely affect the ocular surface, and a reduction of functional meibomian glands can contribute to chronic tear film dysfunction after corneal refractive surgery.

Effect of diquafosol three per cent ophthalmic solution on tear film and corneal aberrations after cataract surgery

BACKGROUND

The aim was to evaluate the effect of diquafosol on tear film parameters and corneal aberrations after cataract surgery.

METHODS

This retrospective, comparative, observational case series included patients who underwent cataract surgery with or without peri-operative use of diquafosol three per cent ophthalmic solution. Patients in group I (31 eyes) were treated with diquafosol three per cent ophthalmic solution six times a day from one week before surgery to three months after surgery. Patients in group II (33 eyes) underwent cataract surgery without being administered diquafosol. Tear film break-up time (BUT), the ocular surface disease index (OSDI), the Oxford Scheme score, Schirmer's test I and corneal aberrations were determined before and at one and three months post-surgery.

RESULTS

In group I, the BUT, OSDI and Oxford Scheme score showed significant improvement at one and three months post-surgery (p = 0.002 for BUT at one month and three months, p = 0.023 and p = 0.049 for OSDI at one month and three months and p = 0.001 and p = 0.026 for Oxford Scheme at one month and three months), compared to baseline. In group II, the BUT, OSDI and Oxford Scheme score did not show any significant improvement during the follow-up period. In both groups, Schirmer's test I significantly decreased at three months post-surgery (p = 0.011 for group I and p = 0.034 for group II), compared to baseline. There were significant differences in the BUT and OSDI between the groups at three months post-surgery (p = 0.037 for BUT and p = 0.011 for OSDI). Regarding the corneal aberration, there were no significant differences between the groups at three months post-surgery.

CONCLUSION

Peri-operative application of diquafosol three per cent ophthalmic solution may prevent dry eye-related ocular surface changes accompanied by improvement of ocular symptom. No definite changes in corneal aberrations were noted.

Photorefractive keratectomy for patients with preoperative low Schirmer test value

Purpose

To compare dry eye signs and symptoms between patients with preoperative low and normal Schirmer test after Photorefractive keratectomy (PRK).

Methods

In this prospective, nonrandomized, comparative case series, 76 eyes of 76 patients were preoperatively categorized into two groups according to selected criteria for characterization of tear film status: the low Schirmer test value (STV) group and the normal STV group. For the tear function assessment, we performed a Schirmer test with and without anesthesia, tear break-up time (TBUT) test, and measurement dry eye symptoms using the Farsi translation of Ocular Surface Disease Index (OSDI) questionnaire pre- and 3 months post-operation.

Results

Postoperatively, the Schirmer and TBUT values were significantly lower in both groups than preoperatively (all p < 0.05). Deterioration in tear secretion was significantly greater in the low STV group (p = 0.012), but tear stability was more compromised in the normal STV group (p = 0.021). The changes in OSDI score were not significant between the two groups.

Conclusion

These results demonstrated that tear function deteriorates after PRK. Therefore, patients with low preoperative Schirmer test values should be thoroughly assessed for dry eye before proceeding with refractive surgery to eliminate postoperative complication.

Effects of adjuvant omega-3 fatty acid supplementation on dry eye syndrome following cataract surgery: A randomized clinical trial

PURPOSE

To investigate the effect of omega-3 polyunsaturated fatty acid supplement on qualitative and quantitative subjective (ocular surface disease index [OSDI]) and objective (Schirmer's test, tear break up time [TBUT], and tear osmolarity) dry eye indices after cataract surgery.

METHODS

In this randomized clinical study, 61 eyes of 48 patients complaining of new onset dry eye symptoms after phacoemulsification were enrolled. Subjects were randomly allocated into two groups using urn randomization. Controls received conventional treatment. The treatment group received omega-3 dietary supplement in addition to conventional therapy.

RESULTS

There was no significant difference between the control and treatment groups in pre-treatment indices of Schirmer (3.50 ± 3.13 and 2.96 ± 3.39, respectively, P = 0.582), TBUT (6.67 ± 1.36 and 4.87 ± 2.22, respectively, P = 0.687), osmolarity (316.66 ± 8.50 and 315.4 ± 17.06, respectively, P = 0.906), and OSDI (32.99 ± 19.03 and 35.32 ± 18.99, respectively, P = 0.635). Mean pre-treatment OSDI in the control group was 32.99 ± 19.03, which improved significantly after treatment to 25.43 ± 14.49 (P = 0.003). The mean pre-treatment OSDI in the treatment group was 35.32 ± 18.99 (range: 7.5-77.77), which improved significantly after treatment to 16.31 ± 13.72 (range: 2.77-47.22) (P < 0.001). OSDI improvement was significantly higher in the treatment group than the control group (P = 0.026). TBUT improved in both the control and treatment groups after treatment (P < 0.001). However, TBUT was affected significantly more in the treatment group compared with the control group (P = 0.038). Mean tear film osmolarity in the control group was 316.67 ± 8.50 (range: 308-325), which improved insignificantly after treatment to 311.33 ± 6.35 (range: 304-315) (P = 0.157). Mean pre-treatment tear film osmolarity in the treatment group was 315.40 ± 17.06 (range: 279-340), which improved significantly after treatment to 296.90 ± 14.39 (range: 260-310) (P < 0.001). Also, post-treatment Schirmer results between the two groups were not statistically significant (P = 0.155).

CONCLUSION

Omega-3 dietary supplements have an additive effect on tear film indices of patients with dry eye syndrome after phacoemulsification.

Dry Eye Disease in Patients with Functioning Filtering Blebs after Trabeculectomy

PURPOSE

The aim of this study was to analyze dry eye disease (DED) in patients with functioning filtering blebs and to explore the relationship between the morphology of filtering blebs and ocular surface instability.

METHODS

This was a cross-sectional, case-comparison study. Seventy glaucomatous patients (70 eyes) with functioning blebs who had undergone trabeculectomy more than 6 months prior (study group) and 35 control subjects (35 eyes) (control group) were included. All subjects completed an ocular symptom questionnaire that referred to the Shihpai Eye Study. Evaluation of meibomian gland obstruction, a tear film break-up time test (TFBUT), fluorescein corneal staining and a Schirmer's tear test were then performed. Filtering bleb morphology was analyzed using Wuerzburg bleb classification scoring criteria in the study group. The presence of DED was defined as the concomitant presence of TFBUT <10 seconds and the presence of superficial punctate keratitis.

RESULTS

The patients with functioning blebs presented higher corneal staining scores (P = 0.012) and lower TFBUT values (P = 0.043) than the control group. DED was present in 28/70 patients in the study group and 6/35 patients in the control group (P = 0.018). More patients in the study group complained of dryness (P = 0.001), a gritty or sandy sensation (P < 0.001) and redness (P = 0.048). In the study group, the patients with DED were significantly different from the patients without DED in both TFBUT (P < 0.001) and corneal staining (P < 0.001). More patients in the DED group were likely to report dryness (P = 0.013) and watery or teary eyes (P = 0.012). The differences in meibomian gland obstruction scores between the study and the control group, the DED and the non-DED group were not significant (P = 0.105 and P = 0.077, respectively). The values for microcysts and bleb heights were significantly higher in the DED group (P = 0.040 and P = 0.011, respectively). A Spearman's rank correlation showed that microcysts were positively correlated with corneal staining (r = 0.270, P = 0.024). Bleb height was negatively correlated with TFBUT (r = -0.299, P = 0.012) and positively correlated with corneal staining (r = 0.275, P = 0.021). The relationships between DED and microcysts and between DED and bleb height were significant (r = 0.247, P = 0.039 and r = 0.307, P = 0.010, respectively).

CONCLUSION

DED is relatively common in patients with functioning filtering blebs following trabeculectomy. In DED patients, dryness and watery are common symptoms. Microcysts and bleb height are related to ocular surface instability and DED.

[Eye lid hygiene in chronic allergic blepharoconjunctivitis patients before laser refractive surgery]

AIM

To evaluate the effectiveness of eyelid hygiene in patients with chronic allergic blepharoconjunctivitis (ABC) as a part of their preparation for laser refractive surgery.

MATERIAL AND METHODS

The study involved 32 patients (12 males and 20 females aged 25-42 years) with refractive errors, namely, compound myopic astigmatism (23 patients) and hyperopic astigmatism (9 patients) suffering from chronic ABC and secondary dry eye syndrome (DES). All the patients initially received a standard treatment for ABC and DES, that is olopatodin hydrochloride instillations - 1 mg/ml 2 times daily, preservative-free hyaluronic acid preparation - 1 mg/ml 3 times daily, and polyacrylic acid and dexpanthenol gel at night for one month. The scheme, however, appeared not effective enough. Hence, the patients were prescribed eyelid hygiene (Blepharolotion or Blepharosalfetka plus Blepharogel-1 2 times daily) to relive meibomian gland dysfunction (MGD). They also underwent a conventional ophthalmic examination, allergy tests, evaluation of ABC and DES signs and symptoms, tear film break-up time test, Schirmer's test, meibomian glands evaluation, optical coherence tomography with meniscometry, xerosis index evaluation, and lissamine green staining for lid wiper epitheliopathy.

RESULTS

At the beginning of the study signs and symptoms of MGD-associated DES were predominant in all patients. Chronic ABC signs were mild. In 2-3 months, meibomian gland function and tear film break-up time improved significantly in most patients, while xerosis index decreased and lid wiper epitheliopathy resolved. Laser refractive surgery (LASIK) was performed in 81.25% of patients, all of whom were satisfied with the results.

CONCLUSION

Inclusion of eyelid hygiene into preoperative management of patients with chronic ABC and DES allows to achieve optimum conditions for laser refractive surgery in most cases.

The course of dry eye after phacoemulsification surgery

BACKGROUND

The aim of this retrospective study was to evaluate the course of dry eye syndrome after phacoemulsification surgery.

METHODS

One hundred and ninety-two eyes of 96 patients (30 males, 66 females) with chronic dry eye syndrome and cataract, who had undergone phacoemulsification surgery were enrolled in this study.

RESULTS

Their mean age was 68.46 ± 8.14 standard deviation (SD) (range 56-83) years . Thirty of them (31 %) were males and 66 (69 %) were females. Ocular Surface Disease Index (OSDI) questionnaire scores increased postoperatively, but arrived preoperative levels at the end of 3rd month following the surgery. Fluorescein staining patterns according to Oxford Schema got worse postoperatively, however after postoperative 3rd month they got better and resembled preoperative patterns. The mean postoperative 1st day, 1st week and 1st month Break-up Time (BUT) values were significantly lower than preoperative BUT value (P < 0.001, P < 0.001, P < 0.001), however 3rd month, 6th month, 1st year and 2nd year values were not significantly different from preoperative value (P = 0.441, P = 0.078, P = 0.145, P = 0.125). The mean postoperative 1st day, 1st week and 1st month Schirmer Test 1 (ST1) values were significantly lower than preoperative ST1 value (P < 0.001, P < 0.001, P < 0.001), however 3rd month, 6th month, 1st year and 2nd year values were not significantly different from preoperative value (P = 0.748, P = 0.439, P = 0.091, P = 0.214).

CONCLUSION

Phacoemulsification surgery may aggravate the signs and symptoms of dry eye and affect dry eye test values in chronic dry eye patients in short-term. However, in long-term, signs and symptoms of dry eye decrease and dry eye test values return to preoperative values.

Rethinking dry eye disease: a perspective on clinical implications

Publication of the DEWS report in 2007 established the state of the science of dry eye disease (DED). Since that time, new evidence suggests that a rethinking of traditional concepts of dry eye disease is in order. Specifically, new evidence on the epidemiology of the disease, as well as strategies for diagnosis, have changed the understanding of DED, which is a heterogeneous disease associated with considerable variability in presentation. These advances, along with implications for clinical care, are summarized herein. The most widely used signs of DED are poorly correlated with each other and with symptoms. While symptoms are thought to be characteristic of DED, recent studies have shown that less than 60% of subjects with other objective evidence of DED are symptomatic. Thus the use of symptoms alone in diagnosis will likely result in missing a significant percentage of DED patients, particularly with early/mild disease. This could have considerable impact in patients undergoing cataract or refractive surgery as patients with DED have less than optimal visual results. The most widely used objective signs for diagnosing DED all show greater variability between eyes and in the same eye over time compared with normal subjects. This variability is thought to be a manifestation of tear film instability which results in rapid breakup of the tearfilm between blinks and is an identifier of patients with DED. This feature emphasizes the bilateral nature of the disease in most subjects not suffering from unilateral lid or other unilateral destabilizing surface disorders. Instability of the composition of the tears also occurs in dry eye disease and shows the same variance between eyes. Finally, elevated tear osmolarity has been reported to be a global marker (present in both subtypes of the disease- aqueous-deficient dry eye and evaporative dry eye). Clinically, osmolarity has been shown to be the best single metric for diagnosis of DED and is directly related to increasing severity of disease. Clinical examination and other assessments differentiate which subtype of disease is present. With effective treatment, the tear osmolarity returns to normal, and its variability between eyes and with time disappears. Other promising markers include objective measures of visual deficits, proinflammatory molecular markers and other molecular markers, specific to each disease subtype, and panels of tear proteins. As yet, however, no single protein or panel of markers has been shown to discriminate between the major forms of DED. With the advent of new tests and technology, improved endpoints for clinical trials may be established, which in turn may allow new therapeutic agents to emerge in the foreseeable future. Accurate recognition of disease is now possible and successful management of DED appears to be within our grasp, for a majority of our patients.

The role of corneal innervation in LASIK-induced neuropathic dry eye

Almost half the patients who undergo laser in situ keratomileusis (LASIK) experience dry eye following the procedure. However, the etiology of LASIK-induced dry eye is unclear. The purpose of this review is to examine and summarize the current evidence for the etiology of LASIK-induced dry eye, with a focus on ocular surface sensitivity and corneal innervation. Evidence suggests that the alteration of corneal nerves after LASIK is the most likely cause of the subjective symptoms of LASIK-induced dry eye, even though corneal sensitivity and the clinical indicators of dry eye return to apparently normal values within a year due to the partial recovery of the corneal nerve plexus. The hypothesis is explored that dry eye symptoms following LASIK may result from abnormal sensation due to LASIK-induced corneal neuropathy. Other factors, such as alterations in conjunctival goblet cell density, might also contribute to the symptoms and signs of LASIK-induced dry eye. Inter-relationships between nerve morphology, tear neuropeptide levels and dry eye require further investigation. A better understanding of this phenomenon may result in improved management of post-LASIK dry eye.

Changes in the tear film and ocular surface after cataract surgery

PURPOSE

To evaluate changes in corneal sensitivity, tear film function, and ocular surface stability in patients after cataract surgery.

METHODS

This hospital-based prospective randomized trial included 48 eyes from 30 patients who underwent phacoemulsification. Slit-lamp examination, Schirmer test 1 (ST1), and measurement of corneal sensitivity and tear film breakup time (BUT) were performed for all patients 1 day before and 1 day, 1 month, and 3 months after surgery. In addition, conjunctival impression cytology from the temporal region of the conjunctiva was simultaneously performed.

RESULTS

Corneal sensitivity at the center and temporal incision sites had decreased significantly at 1 day postoperatively (P = .021, P < .001). However, the sensitivity had returned to almost the preoperative level 1 month postoperatively. The mean postoperative ST1 results were no different from preoperative values. On the other hand, BUT results had decreased significantly at 1 day postoperatively (P = .01) but had returned to almost the preoperative level 1 month postoperatively. Mean goblet cell density (GCD) had decreased significantly at 1 day, 1 month, and 3 months postoperatively (P < .001). In addition, decrease in GCD and cataract operative time were highly correlated (r² = 0.65).

CONCLUSIONS

The decrease in GCD, which was correlated with operative time, had not recovered at 3 months after cataract surgery. Therefore, microscopic ocular surface damage during cataract surgery seems to be one of the pathogenic factors that cause ocular discomfort and dry eye syndrome after cataract surgery.

MMP-9 and the perioperative management of LASIK surgery

PURPOSE OF REVIEW

Hyperosmolarity is a central mechanism causing ocular surface inflammation and eye irritation in typical patients suffering from tear dysfunction. Tear composition in dry eyes, or dysfunctional tear syndrome, may destabilize the tear film and cause ocular surface epithelial disease. Increased activity of matrix metalloproteinases (MMPs), especially MMP-9, plays a critical role in wound healing and inflammation and is primarily responsible for the pathologic alterations to the ocular surface that leads to a dysfunctional tear state.

RECENT FINDINGS

Altered corneal epithelial barrier function is the cause for ocular irritation and visual morbidity in dry eye disease. The increased MMP-9 activity in dry eyes may contribute to deranged corneal epithelial barrier function, increased corneal epithelial desquamation, and corneal surface irregularity.

SUMMARY

Dry eye is one of the most common complications of photorefractive keratectomy and laser in-situ keratomileusis (LASIK). LASIK has both a neurotrophic effect on the cornea and leads to a physical change in corneal shape that results in a change in tear dynamics, leading to ocular surface desiccation. The reduction in tear function after LASIK may induce an increase in osmolarity and consequently raise the concentration of proinflammatory cytokines and MMP-9 in the tear film, which results in dry eyes and insufficient attachment between the corneal flap and the corneal bed. Appropriate diagnosis and management of dysfunctional tear syndrome may lead to less postoperative LASIK complications.

"Healthy" eye in office-like environments

Eye irritation symptoms, e.g. dry eyes, are common and abundant symptoms reported in office-like environments, e.g. aircraft cabins. To improve the understanding of indoor related eye symptomatology, relevant knowledge from the ophthalmological and indoor environmental science literature has been merged. A number of environmental (relative humidity, temperature, draft), occupational (e.g. visual display unit work), and individual (e.g. gender, use of cosmetics, and medication) risk factors have been identified, which are associated with alteration of the precorneal tear film (PTF); these factors may subsequently exacerbate development of eye irritation symptoms by desiccation. Low relative humidity including reduced atmospheric pressure further increases the water evaporation from an altered PTF; in addition, work with visual display units may destabilize the PTF by lower eye blink frequency and larger ocular surface. Results from epidemiological and clinical studies support that relative humidity >40% is beneficial for the PTF. Only few pollutants reach high enough indoor concentrations to cause sensory irritation of the eyes, while an altered PTF may exacerbate their sensory effect. Sustained low relative humidity causes impairment of the PTF, while its stability, including work performance, is retained by low gaze and intermittent breaks.

Clinical evaluation of changes in cornea and tear film after surgery for trachomatous upper lid entropion

PURPOSE

To determine the effect of entropion surgery on corneal health in terms of surface epithelium, tear film stability, change in curvature and vision.

METHODS

Prospective study; included consecutive patients with trachomatous upper lid entropion undergoing corrective surgery. Corneal opacity and other conditions that reduced vision were recorded. Best-corrected visual acuity, corneal fluorescein staining, tear film break-up time, Schirmer I test, and keratometry were performed before and after surgery. Data were analysed using Student's t-test, chi(2) test, one-way ANOVA, one-sample t-test, and logistic and multiple regression.

RESULTS

Thirty-six female and 15 male patients with an average age of 59.1+/-10.65 years were included. Lenticular and retinal causes resulted in blindness (P=0.008), and low vision (P=0.02), more often than entropion. At 90 days after surgery, vision improved by 0.55+/-1.48 lines (P=0.01). Superficial punctate staining of the cornea reduced by half over 1-15 days (average 6.96+/-4.99) after surgery, and completely in 1-90 days (average 26.15+/-17.49). Tear film break-up time (range: 3-20 s preoperatively) improved significantly after surgery (P=0.005) whereas Schirmer I (range: 10-35 mm preoperatively) and keratometry values showed insignificant change.

CONCLUSIONS

Surgery for entropion results in healing of superficial keratopathy, improves tear film stability, and the realigned lid margin spreads tears evenly and efficiently, thus contributing to improved vision. These changes, taking place over 1-90 days, should be kept in mind when planning intraocular surgery, keratoplasty, or keratorefractive procedures after entropion correction.

Komplikationen der Excimerlaser-Chirurgie zur Behandlung von Refraktionsfehlern

In surface ablation, haze is the most frequent complication. After LASIK, microkeratome-related complications are rare today and usually resolve without sequelae, provided no ablation was done. Postoperative flap complications such as flap slippage usually occur during the first few days after surgery and should be treated as early whenever present. Interface complications are a new diagnostic entity as the interface between flap and stroma presents a space where fluid or cells can accumulate. Diffuse lamellar keratitis usually occurs within the first few postoperative days and should be treated aggressively to avoid scarring. Epithelial ingrowth is another rare complication usually requiring treatment. Corneal hydrops with fluid accumulation in the interface is a very rare but important phenomenon related to steroid-induced glaucoma but presenting with false low tonometry readings. Corneal ectasia is extremely rare and in most cases related to thin stromal beds. However, its pathogenesis is not yet completely understood, and it may occur in "normal" eyes, too. Dry eye syndrome is the most frequent complication after LASIK. It is usually benign but may cause significant visual impairment in rare cases.

Lipid tear deficiency in persistent dry eye after laser in situ keratomileusis and treatment results of new eye-warming device

PURPOSE

To determine whether lipid tear deficiency is a significant pathogenic factor in persistent dry eyes after laser in situ keratomileusis (LASIK).

SETTING

Ocular Surface Center, Miami, Florida, USA.

METHODS

Thirty-four eyes of 17 patients (mean 46.35 years +/- 11 [SD]) complaining of persistent dryness more than 12 months after LASIK were prospectively studied by symptom scoring and kinetic analysis of tear interference image, tear breakup time, and fluorescein clearance test. Once patients had been clear of inflammation and treated for aqueous tear deficiency, lipid tear deficiency was further confirmed and treated with Eyefeel (Kao, Inc.), an eye-warming device, 4 times daily for 4 weeks.

RESULTS

Sixteen patients were asymptomatic before LASIK but dryness persisted for 41 +/- 19.3 months. Delayed tear clearance was observed in 15 patients (88.2%) and floppy lids in 12 patients (70.5%). Aqueous tear deficiency was reconfirmed in 16 eyes (53.3%). After Eyefeel treatment, there was a subjective improvement of ocular surface diseases index from 60.6 +/- 10.6 to 25.8 +/- 18.5 (P = .0007). Tear breakup time was improved from 2.4 +/- 3.9 seconds to 7.9 +/- 3.6 seconds (P = .004). There was a tear interference pattern change from a vertical lipid tear deficiency to a horizontal normal in 7 eyes. There was a mean lipid spread time improvement from 1.3 +/- 0.4 sec to 0.8 +/- 0.4 sec (P = .001), and there was a mean lipid thickness improvement from 63.5 +/- 23 nm to 79.5 +/- 27 nm (P = .04).

CONCLUSION

Persistent nature of dry eye after LASIK is attributed to in part to delayed tear clearance, undercorrected aqueous tear deficiency, and nonrecognized lipid tear deficiency.