Algebraic formulas characterizing an alternative to Guyton's graphical analysis relevant for heart failure.

Although Guyton's graphical analysis of cardiac output-venous return has become a ubiquitous tool for explaining how circulatory equilibrium emerges from heart-vascular interactions, this classical model relies on a formula for venous return that contains unphysiological assumptions. Furthermore, Guyton's graphical analysis does not predict pulmonary venous pressure, which is a critical variable for evaluating heart failure patients' risk of pulmonary edema. Therefore, the purpose of the present work was to use a minimal closed-loop mathematical model to develop an alternative to Guyton's analysis. Limitations inherent in Guyton's model were addressed by 1) partitioning the cardiovascular system differently to isolate left ventricular function and lump all blood volumes together, 2) linearizing end-diastolic pressure-volume relationships to obtain algebraic solutions, and 3) treating arterial pressures as constants. This approach yielded three advances. First, variables related to morbidities associated with left ventricular failure were predicted. Second, an algebraic formula predicting left ventricular function was derived in terms of ventricular properties. Third, an algebraic formula predicting flow through the portion of the system isolated from the left ventricle was derived in terms of mechanical properties without neglecting redistribution of blood between systemic and pulmonary circulations. Although complexities were neglected, approximations necessary to obtain algebraic formulas resulted in minimal error, and predicted variables were consistent with reported values.

Topical Eugenol Successfully Treats Experimental Candida albicans-Induced Keratitis.

PURPOSE: To determine the efficacy of eugenol for the treatment of Candida keratitis in an experimental model. METHODS: The in vitro antifungal activity of eugenol and fluconazole was tested against C. albicans strains via the microbroth dilution method. An experimental model of Candida albicans keratitis was used. Rabbits were classified into those that received no treatment (control; group 1) and those that started eugenol treatment immediately (group 2) or after 4 days (group 3) of keratitis induction (n = 12-16 rabbits/group). The 2 treatment groups were assigned to 50 µL of 4 mg/mL eugenol drops hourly for 15 days, while the control group received saline. Corneal penetration of eugenol was measured using HPLC, and corneal toxicity was evaluated clinically and histopathologically. RESULTS: The in vitro minimum inhibitory concentrations of eugenol and fluconazole against C. albicans were 2 and > 0.4 mg/mL, respectively. A 4-mg/mL preparation of eugenol in propylene glycol was the maximum nontoxic dose on rabbit corneas as suggested by clinical and histopathologic findings. At least 75% of all eugenol-treated eyes recovered from keratitis, with improvement in the remaining 25% of the eyes compared to controls. CONCLUSIONS: Eugenol can act as a natural, safe, and effective treatment for fungal keratitis, regardless of whether treatment is started immediately or after 4 days of keratitis induction.

Eye platelet-rich plasma in the treatment of ocular surface disorders.

PURPOSE OF REVIEW: Blood-derived products [autologous serum, eye platelet-rich plasma (E-PRP), plasma rich in growth factors] are successful therapies for ocular surface disorders, which compromise the integrity of the cornea surface and conjunctiva. RECENT FINDINGS: The most noteworthy and recent research has been directed towards hemoderivatives that include platelets. PRP for ophthalmologic use (E-PRP) has achieved successful outcomes as reported in the peer-review literature in the treatment of dry eye, post-laser in-situ keratomileusis ocular surface syndrome, dormant ulcers, and for ocular surface surgical reconstruction after corneal perforation associated to amniotic membrane transplantation, bovine pericardium membrane transplantation, or autologous fibrin membrane combined with solid PRP clot. SUMMARY: PRP is a portion of the patient's own blood having a platelet concentration above baseline. The main advantage of PRP over other products is the presence of the platelets and associated with this the prolonged release of growth factors that are involved in the wound healing process of the cornea and conjunctival surface. E-PRP seems to be a reliable and effective therapeutic approach to enhance epithelial wound healing and promote ocular surface regeneration in different pathological conditions.

A qualitative analysis of adolescent motherhood within the broader family context in Peru.

Objective: The purpose of this study was to characterize the impact of adolescent pregnancy on families and describe the needs of adolescent mothers and their infants in order to assess the need for intervention and identify potential intervention targets. Background: Adolescent mothers and their offspring face an increased risk of mental health problems. Adolescent mothers and their families also face significant resource constraints; 95% live in low- and middle-income countries (LMICs). Cost-effective interventions are needed to improve outcomes for this vulnerable group. Method: This qualitative study conducted in Lima, Peru, consisted of four clinician focus groups and 18 in-depth interviews with adolescent mothers and their family members. Data were coded thematically, and direct content analysis was employed. Results: The study identified the following issues facing adolescent parents: the transition to parenthood, the need for family support, difficulty accessing support, the difficulty for family members of providing support, and ideas about responsibility and adolescent autonomy. Conclusion: Overall, these findings demonstrate the need for interventions that engage families and address barriers to accessing support, including relationship conflict and differing beliefs about responsibility and autonomy. Implications: Interventions are needed for adolescent mothers in LMICs that mobilize family support. Clinicians who care for these patients need to be aware of the family context and the resources available where they practice.

Clinical Evaluation of a New Spectral-Domain Optical Coherence Tomography-Based Biometer.

The VEMoS-AXL system is a new optical biometer based on spectral domain optical coherence tomography (SD-OCT) that has been tested in terms of intrasession repeatability and compared with a swept-source optical coherence tomography biometer (SS-OCT), which is recognized as the gold standard for the performance of an agreement analysis. A biometric analysis was performed three consecutive times in 120 healthy eyes of 120 patients aged between 18 and 40 years with the SD-OCT system, and afterwards, a single measurement was obtained with the SS-OCT system. Within-subject standard deviations were 0.004 mm, 4.394 µm, and 0.017 mm for axial length (AL), central corneal thickness (CCT), and anterior chamber depth (ACD) measures obtained with the SD-OCT biometer, respectively. The agreement between devices was good for AL (limits of agreement, LoA: -0.04 to 0.03 mm) and CCT (LoA: -4.36 to 14.38 µm), whereas differences between devices were clinically relevant for ACD (LoA: 0.03 to 0.21 mm). In conclusion, the VEMoS-AXL system provides consistent measures of anatomical parameters, being most of them interchangeable with those provided by the SS-OCT-based gold standard.

Effect of platelet-rich plasma in nerve regeneration after LASIK.

PURPOSE: To investigate the effect of topical eye application of platelet-rich plasma (E-PRP) on the recovery of corneal sensitivity after LASIK and the anatomical recovery of the sub-basal corneal plexus as studied by confocal microscopy. METHODS: This was a randomized, consecutive, controlled, prospective and masked study on 108 myopic eyes receiving LASIK. The main variables of the study were the increase in corneal sensitivity (Cochet-Bonet aesthesiometer; Luneau, Paris, France) and the aspect of the sub-basal nerve plexus (confocal microscope). Additionally, a biomicroscopic study of the epithelial status of the cornea and a subjective questionnaire were completed. Each eye of each patient was assigned to one of two groups: 54 eyes treated with balanced saline solution and 54 fellow eyes receiving PRP drops for 3 months. RESULTS: No significant differences were detected when the corneal sensitivity thresholds were compared at any postoperative visit in both groups (P > .05 for all comparisons). Almost identical sub-basal fiber densities were estimated for both groups before LASIK (t test, P = .66). However, the type and severity of staining detected during the slit-lamp examinations at the first and third month postoperatively were significantly less evident in the E-PRP treatment group (Wilcoxon test, P < .05). CONCLUSIONS: PRP drops have beneficial effects for promoting epithelial status after LASIK but have no positive effect on recovery of corneal sensitivity, probably due to the limited bioavailability of growth factors in corneal stroma when the substance is topically administered.

Manifestations of Intergenerational Trauma During the Perinatal Period Among Adolescent Mothers in Lima, Peru: A Qualitative Analysis.

Adverse childhood experiences have a lasting impact on health across the life course. The perinatal period offers a unique opportunity to rework problematic dynamics in families experiencing intergenerational trauma. This study explores the family dynamics that are activated during the perinatal period and considers the potential for intervention with adolescent parents and their families in Lima, Peru. This narrative analysis was part of a broader study that included focus groups and in-depth interviews. Of the ten adolescent mothers interviewed, four narratives were selected for presentation in this manuscript. These particular narratives were selected to illustrate the diversity of the experiences among this group and for the exceptional level of detail provided about their life experiences and family relationships. Narrative excerpts were analyzed in the context of the entire interview and the aggregate content of other interviews in order to explore both explicit and implicit meanings. This study identified critical relational shifts among adolescent parents and their families during the perinatal period. In one instance, adolescent parenthood created an opportunity for the family to come together. In the other cases, conflict escalated, relations grew distant, or both. These narrative data demonstrate that intergenerational trauma can interfere with family relationships in the context of adolescent pregnancy and prevent adolescent parents from accessing needed support from their families. Intervention with families could address the impact of trauma and improve communication and collaboration.

Demographic Features, Physical Examination Findings, and Medication Use in Hospitalized, Delirious Patients With and Without COVID-19 Infection: A Retrospective Study.

BACKGROUND: Delirium is common in the setting of infection with severe acute respiratory syndrome coronavirus 2. Anecdotal evidence and case reports suggest that patients with delirium in the setting of Coronavirus 2019 (COVID-19) may exhibit specific features, including increased tone, abulia, and alogia. OBJECTIVE: To determine whether differences exist in sociodemographic and medical characteristics, physical examination findings, and medication use in delirious patients with and without COVID-19 infection referred for psychiatric consultation. METHODS: We undertook an exploratory, retrospective chart review of 486 patients seen by the psychiatry consultation service at a tertiary care hospital from March 10 to May 15, 2020. Delirious patients were diagnosed via clinical examination by a psychiatric consultant, and these patients were stratified by COVID-19 infection status. The strata were described and compared using bivariate analyses across sociodemographic, historical, objective, and treatment-related variables. RESULTS: A total of 109 patients were diagnosed with delirium during the study period. Thirty-six were COVID-19+. Median age was 63 years and did not differ between groups. COVID-19+ patients with delirium were more likely to present from nursing facilities (39% vs 11%; Fisher's exact test; P = 0.001) and have a history of schizophrenia (11% vs 0%; Fisher's exact test; P = 0.011). Myoclonus (28% vs 4%; P = 0.002), hypertonia (36% vs 10%; P = 0.003), withdrawal (36% vs 15%; P = 0.011), akinesia (19% vs 6%; P = 0.034), abulia (19% vs 3%; P = 0.004), and alogia (25% vs 8%; P = 0.012) were more common in COVID-19+ patients. COVID-19+ delirious patients were significantly more likely to have received ketamine (28% vs 7%; P = 0.006), alpha-adrenergic agents besides dexmedetomidine (36% vs 14%; P = 0.014), and enteral antipsychotics (92% vs 66%; P = 0.007) at some point. CONCLUSIONS: Patients with COVID-19 delirium referred for psychiatric consultation are more likely to reside in nursing facilities and have a history of schizophrenia than delirious patients without COVID-19. Patients with delirium in the setting of COVID-19 may exhibit features consistent with akinetic mutism. Psychiatrists must assess for such features, as they may influence management choices and the risk of side effects with agents commonly used in the setting of delirium.

Cosmetic Keratopigmentation in Sighted Eyes: Medium- and Long-term Clinical Evaluation.

PURPOSE: To assess the medium- and long-term outcomes of keratopigmentation (KTP) as a surgical alternative to change the cosmetic appearance of healthy eyes. METHODS: A prospective, interventional, consecutive, multicenter, series of cases of cosmetic KTP was included in the study. Forty consecutive patients underwent KTPs with mineral micronized pigments using a femtosecond laser-assisted intrastromal or superficial technique. Main outcomes were cosmetic evaluation, subjective patients' satisfaction, and complications. The outcomes were evaluated at 6 months after the last operation and then yearly. RESULTS: This study included 79 eyes of 40 patients, with a mean age of 34 ± 11 years; femtosecond laser-assisted intrastromal keratopigmentation was performed in 39 patients (97.5%) and superficial automated keratopigmentation in 1 patient. Mean follow-up was 29 months (range 6-69). Observer's evaluation was excellent in 90% of cases, and patient's satisfaction was excellent in 92.5% of cases. Twenty-eight eyes (35.4%) were reoperated; of them, 7 eyes (8.9%) had 2 color touch ups and 4 eyes (5.1%) had 3 color touch ups. After the retreatments, all the patients were satisfied with the cosmetic aspect. Light sensitivity at first month was the most common complication (30%), followed by change in the color (7.5%), color fading (5%), and visual field limitations in a case with 4.5-mm pupil size (2.5%). One patient with a previous laser in situ keratomileusis developed corneal ectasia. CONCLUSIONS: Cosmetic KTP achieves good cosmetic results and is associated with high patient satisfaction. Most of the complications could be managed adequately. It might offer a safe and effective new surgical alternative for those patients motivated to change the apparent color of their eyes.

Pyrenochaeta keratinophila sp. nov., isolated from an ocular infection in Spain.

The new coelomycete Pyrenochaeta keratinophila, isolated from corneal scrapings of a case of keratitis in Spain, is described and illustrated. This fungus is morphologically characterized by grey-olivaceous to greenish olivaceous colonies, scarce pycnidial setae placed mainly near the ostiole and production of phialoconidia from the aerial mycelium. The latter feature is unknown in any other species of the genus Pyrenochaeta. Sequencing of the ITS rDNA region of this clinical strain confirmed this proposal and revealed its close genetic relationship with the Leptosphaeriaceae.

Quantification of Growth Factors and Fibronectin in Diverse Preparations of Platelet-Rich Plasma for the Treatment of Ocular Surface Disorders (E-PRP).

Purpose: The purpose of this study was to quantify the presence of growth factors (GFs) and fibronectin in autologous platelet-rich plasma for topical ocular use (E-PRP) comparing their concentration when different preparation and preservation procedures were applied. Methods: E-PRP was prepared with blood from healthy volunteers. The count of platelets, leukocytes, and red blood cells in the whole blood and E-PRP were performed. The concentration of the GFs platelet-derived growth factor BB (PDGF-BB), transforming growth factor ß1 (TGF-ß1), epidermal growth factor (EGF), vascular endothelial growth factor A (VEGF-A), and fibronectin was determined in each of the four procedures applied including fresh, frozen at -20°C for 3 months, fresh-spin, and frozen-spin at -20°C E-PRP samples. Posterior statistical analysis was performed to establish significant differences between groups and between GFs in relation to the amounts of platelets. Results: Platelets in the E-PRP doubled in the number of basal values of whole blood (P ≤ 0.01). The blood cells in the E-PRP decreased drastically in red cells (99%) and also in leukocytes (82%). The concentration of PDGF-BB and EGF was significantly higher (P < 0.01) when the E-PRP samples were frozen at -20°C. However, no significant differences were observed for TGF-ß1, VEGF-A, and fibronectin (P > 0.05). The concentration of GFs in the E-PRP did not necessarily correlate with the number of platelets. Conclusions: Freezing the E-PRP for 3 months at -20°C increased the concentration of important proteins, such as PDGF-BB and EGF, and maintained the levels of others. These findings are essential because treatments, such as E-PRP, used by patients with ocular surface dysfunctions tend to prolong it in time. In addition, subsequent centrifugation of the E-PRP decreased the values of TFG-ß1, but not the other GFs, which would allow adjusting the concentration of TFG-ß1, as necessary. This procedure guarantees their correct conservation and viability. Translational Relevance: This work demonstrates how clinical application can be improved by starting from basic research. The quantification of GFs and fibronectin in platelet-rich plasma (PRP) helps to clarify which is the best mode of preparation and preservation of PRP for clinical applications. This allows to optimize the product that is delivered to the patients as a treatment for the dysfunctions of the ocular surface, guaranteeing that the conservation does not affect at all the quality of the PRP that it is going to be used.

Keratopigmentation combined with strabismus surgery to restore cosmesis in eyes with disabling corneal scarring and squint.

BACKGROUND: Therapeutic corneal pigmentation has modernly evolved into different sophisticated techniques to camouflage cosmetically disabling corneal opacities and scars with good reported outcomes. Blind eyes frequently suffer from strabismus which further deteriorates the cosmesis of the patient. Combined keratopigmentation (KTPG) with strabismus surgery may be an option for these patients. METHODS: A total of 72 consecutive patients were retrospectively reviewed in this investigation. Main outcome measures were postoperative residual squint, and cosmesis evaluated by an independent observer, patient satisfaction, reoperation rates for KTPG and squint, and complications. RESULTS: A total of 72 consecutive patients and 73 eyes that underwent KTPG and strabismus surgery were included in this study. Mean follow-up time was 2.5±3 years. Patient age ranged from 5 to 83 years, with 93% having visual acuity worse than 0.1. 14 eyes (24.5%) underwent repeated KTPG, 24 (42.1%) had repeated strabismus surgery. 14 patients (19.4%) had a repeat muscle surgery, although 55 (76.4%) of the 72 patients achieved orthotropia or had deviations within 10 prism dioptres at the end of the follow-up period. Corneal microperforation was encountered in two (2.8%) patients and conjunctival staining in 10 eyes. Cosmesis was good for all patients. Patients who required repeat KTPG or strabismus surgery, or those in whom orthotropia was not totally restored, considered their cosmetic appearance sufficiently improved. CONCLUSION: Corneal KTPG combined with strabismus surgery provides good cosmesis for patients with corneal scarring and strabismus with minimal complications. Reoperation rates are relatively high in the short term to accomplish an optimal cosmetic result.

New pyrenochaeta species causing keratitis.

We report a new fungus as an agent of fungal keratitis in a diabetic woman. The fungal etiology was established by classic microbiology and PCR following 3 months of antibacterial therapy. The morphological features of the isolate and sequence analysis of the internal transcribed spacer region indicate a new species of Pyrenochaeta (Coelomycetes).

Treatment of Severe Keratoconus Hydrops With Intracameral Platelet-Rich Plasma Injection.

PURPOSE: To present successful management of severe corneal hydrops by corneal optical coherence tomography (OCT) guidance and intracameral application of eye platelet-rich plasma (E-PRP) in a case with Down syndrome. METHODS: A 36-year-old woman with Down syndrome presented with acute vision loss, pain, photophobia, and corneal edema in the left eye. Clinical examination revealed keratoconus in the right eye and extreme keratoconus with severe corneal hydrops in the left eye. Anterior segment OCT (MS-39, Costruzione Strumenti Oftalmici, Firenze, Italy) showed intrastromal cystic fluid collection and ruptured and detached Descemet membrane. The OCT-guided management of hydrops is first described in this case report. RESULTS: Medical treatment and intracameral sulfur hexafluoride injection failed. A sterile 0.3 mL of E-PRP was injected into the anterior chamber. Clinical and anatomical improvement began from the first postoperative day, and corneal edema totally resolved at 1 week. Postoperatively, no significant side effect was noted except an early transient moderate (28 mm Hg) intraocular pressure peak. Anterior segment-OCT demonstrated dramatic normalization in corneal morphology with total disappearance of fluid in the cystic intracorneal space, closure of the DM rupture, and DM reattachment. The patient was stable during the 6-month follow-up. CONCLUSIONS: In this case, intraocular E-PRP was a promising, apparently safe, and effective treatment option in management of corneal hydrops, in which conventional approaches failed. This is the first case in the literature to describe OCT appearance of corneal hydrops and intracameral use of E-PRP for the resolution of DM rupture in acute corneal hydrops.

Superficial Keratopigmentation: An Alternative Solution for Patients With Cosmetically or Functionally Impaired Eyes.

PURPOSE: To report the use of different superficial keratopigmentation (KTP) techniques for restoring or enhancing cosmetic appearance of eyes impaired for several reasons. METHODS: This is a retrospective, consecutive, noncomparative interventional series of cases, in which 136 cosmetically disabled eyes (due to different corneal abnormalities) of 130 patients were included. A total of 222 procedures of superficial manual KTP and superficial automated KTP were performed. The procedures were divided into 2 groups: first and second-stage procedures. The patients' cosmetic appearance and satisfaction were evaluated and graded as excellent, good, or poor. RESULTS: A total of 222 procedures were performed, 57.2% were superficial automated KTP, 22.5% were superficial manual KTP, and 20.3% included the combination of superficial KTP with other KTP techniques. Six procedures were purely cosmetic, 16 therapeutic functional, and 200 therapeutic cosmetic. Superficial KTP, as a second-stage procedure, was performed in 13 eyes that were previously pigmented by intrastromal techniques. Superficial KTP as an initial indication (first-stage procedure) alone or in combination with another KTP technique in the same surgery was performed in 123 eyes, in which 44.7% of them were reoperated once or more. Best-corrected visual acuity changed insignificantly, and the intraocular pressure decreased significantly in all the studied groups. No intraoperative complications were observed, 11.2% of eyes with a follow-up time of more than 3 months developed postoperative complications. Most of the patients (98.5%) were satisfied. CONCLUSIONS: The modern superficial KTP procedure provides the possibility to improve the cosmetic appearance of impaired eyes, as an alternative to evisceration, enucleation, prosthetic contact lenses, or keratoplasty.

Treatment of chronic and extreme ocular hypotension following glaucoma surgery with intraocular platelet-rich plasma: A case report.

PURPOSE: To report a new approach for the treatment of severe ocular hypotony secondary to glaucoma filtering surgery with mitomycin C by injecting autologous eye platelet-rich plasma (E-PRP) in the anterior chamber to block excessive diffuse filtration through an abnormally thinned sclera. METHODS: A 49-year-old patient with the Axenfeld-Rieger syndrome and severe chronic hypotony and corneal edema following filtering glaucoma surgery with mitomycin C received an isolated injection of 0.3 mL of autologous platelet-rich plasma in the anterior chamber. RESULTS: Intraocular pressure measured by Goldman's applanation tonometry 6 h after the procedure improved to 18 mmHg. Intraocular pressure remained stable along the full follow-up period of 6 month. No filtration or hypotony or any other complications were observed. CONCLUSION: Intracameral platelet-rich plasma (E-PRP) injection was an effective, rapidly effective, and safe procedure for treatment of severe chronic ocular hypotony following glaucoma filtrating surgery.

Keratopigmentation with micronised mineral pigments: complications and outcomes in a series of 234 eyes.

AIM: To report the complications observed in a consecutive large series of cases treated with keratopigmentation (KTP). METHODS: KTP was performed in 234 eyes of 204 patients for therapeutic and cosmetic reasons. From them, 50 eyes of 29 patients suffered complications. Different KTP techniques and three generations of pigments (GP) were used. The follow-up period ranged from 4 months to 12 years. Light sensitivity (LS), visual field (VF) limitations and MRI alterations were considered functional complications. Organic complications were described as change in colour, colour fading and neovascularisation. RESULTS: The percentage of complications was 12.82%. Most patients complained of LS (49%), then colour fading and change in colour (19%). Neovascularisation, VF limitations and MRI complications constituted 7%, 4% and 2%, respectively. Organic complications were observed with the previous GP but resolved with the latest third GP with CE mark certification (Conformité Européene). Although LS remained with the corneal-specific pigments, it gradually disappeared in most of the patients (81.81%) 6 months postoperatively. CONCLUSION: To the best of our knowledge this is the first time a study systematically and comprehensively approaches and reports KTP complications. KTP with third GP provides better results and fewer complications than previous ones. It is a modern, minimally invasive technique that helps solve several functional ocular problems and improves cosmetic appearance of the patients. Dermatological pigments should not be used as they lead to complications; instead pigments specifically tested for the eye in terms of toxicity and teratogenicity should be used.

Treatment with platelet-rich plasma of surgically related dormant corneal ulcers.

PURPOSE: To assess the effectiveness of autologous platelet-rich plasma for the treatment of dormant corneal ulcers secondary to corneal surgery and unresponsive to conventional treatment. SETTING: VISSUM, Ophthalmology Institute of Alicante, Alicante, Spain. DESIGN: Prospective nonrandomized, observational consecutive study. METHODS: A total of 44 eyes of 28 patients with dormant corneal ulcers secondary to corneal surgery were included in a prospective study and treated with autologous platelet-rich plasma during 6 weeks. Wilcoxon signed-rank test was used to compare the effect of the treatment. RESULTS: In all, 28 patients (65.1%) improved their visual acuity at least one line in Snellen chart, 26 (59.09%) had a decrease in the size of the ulcer or even a total closure, and 40 (90.9%) experienced an improvement in their symptoms. The results are also provided for the four groups of patients (keratoplasty, refractive surgery, cross-linking, and chronic postsurgical corneal edema). CONCLUSION: Platelet-rich plasma eye drops shows to be a good option for the treatment of dormant corneal ulcers secondary to corneal surgery.

Comparison of goblet cell density after femtosecond laser and mechanical microkeratome in LASIK.

PURPOSE: To study the effect of the LASIK procedure performed with a femtosecond laser and a manual microkeratome on the conjunctival goblet cell and epithelial cell populations. METHODS: In this prospective, nonrandomized, masked study, 64 eyes undergoing LASIK were included: 30 with the Moria M2 (M2) microkeratome and 34 with the IntraLase femtosecond laser (IL). The preoperative spherical equivalent was -2.0 +/- 3.8 D in the M2 group and -3.1+/- 3.1 D in the IL group. The time that the suction ring was applied on the eye was registered, and goblet cell density (GCD), epithelial cell morphology, and inflammatory cells were evaluated by conjunctival impression cytology, before and after the surgery. RESULTS: All the patients in both groups showed a decrease in GCD after LASIK (P < 0.001) that recovered after 6 months. At 1 week, 1 month, and 3 months, GCD was lower with IL than with M2 (P < 0.019, P < 0.001, and P < 0.024, respectively). The mean period that the suction ring was applied was longer in the IL than in the M2 group (P < 0.001). There was a high correlation between the decrease in GCD and the suction time (R = 0.8), and the preoperative spherical equivalent (R congruent with 0.4). CONCLUSIONS: Impression cytology showed a greater reduction in goblet cell populations after IL than after M2, probably because of the length of time that the suction ring exerted pressure on the conjunctiva. These changes in the goblet cells may contribute to the development of the ocular surface syndrome after LASIK procedures.

Effect of suction ring application during LASIK on goblet cell density.

PURPOSE: To study the effect of LASIK surgery on conjunctival goblet cells as one of the proposed mechanisms for dry eye occurring after LASIK. METHODS: This prospective study included 22 eyes (11 patients) that underwent LASIK for the correction of myopia. Three pairs of samples were taken from the bulbar conjunctiva of each eye. The first pair was taken preoperatively before application of the suction ring. The second and third pairs were taken from the same sites at 1 week and 1 month consecutively. The first site was at 12 o'clock and the second at the inferotemporal quadrant between 7 and 8 o'clock. Time of suction was recorded. RESULTS: Preoperatively, mean goblet cell density was 424 +/- 105 cells/mm2 (range: 284 to 630 cells/mm2). All postoperative samples showed a statistically significant decrease in goblet cell count: 216 +/- 81 cells/mm2 (range: 40 to 325 cells/mm2) at 1 week and 218 +/- 99 cells/mm2 (range: 50 to 396 cells/mm2) at 1 month. Other parameters of conjunctival impression cytology were normal. The difference between the samples in the inferior conjunctiva preoperatively and 1 week postoperatively was greater than that of the superior conjunctiva. Recovery rate in both sites was similar and the damage did not correlate with the duration of suction. CONCLUSIONS: The application of the microkeratome suction ring induced changes in the perilimbic conjunctiva. These changes contribute to the pathology of dry eye. Goblet cell count remains affected at 1 month postoperatively.