Late-Onset Chronic Corneal Fistula Following Phototherapeutic Keratectomy: A Case Report and Importance of Early Detection.

BACKGROUND We report a case of late-onset chronic fistula in a decompensated cornea after multiple ocular surgeries and a recent phototherapeutic keratectomy (PTK). CASE REPORT A 73-year-old woman presented to our service with a past ocular history of bilateral chronic angle closure glaucoma and pseudophakic bullous keratopathy in the left eye. Given a history of long-term uncontrolled glaucoma with advanced disc cupping and poor visual potential, the patient underwent multiple palliative procedures, including, most recently, a PTK. Few years later she presented with a spontaneous late onset of slowly appearing corneal leak on fluorescein staining upon routine clinical examination. Corrected distance visual acuity was hand motion and intraocular pressure (IOP) was 40 mmHg in the affected eye. Serial anterior segment optical coherence tomography (AS-OCT) sections were obtained, which aided in understanding the current presentation and revealed distinctive multilayer corneal changes during the healing process. The patient was successfully managed with cyanoacrylate corneal gluing and ocular hypotensive medications, which halted the corneal leak. CONCLUSIONS We report a case of a rare finding of corneal fistula in an eye with multiple previous ocular surgeries, and provide an explanation of the possible etiopathogenesis. We also highlight the pivotal role of AS-OCT for evaluating such cases and stress the importance of early detection of similar subtle leaks in the setting of a formed anterior chamber, which can often be missed, carrying a risk of infection.

P04-A115†Serum containing organ culture of the human cornea - still state of the art?

PURPOSE: For decades, human corneas are prepared and stored in specialized tissue banks prior to transplantation. Especially in Europe, storage takes place in 'organ culture', the storage in cell culture medium at approximately physiological temperature. Traditionally, a serum-containing medium is used for this purpose. However, the use of fetal calf serum has considerable disadvantages: there is a risk of disease transmission, availability may not always be guaranteed in the necessary quality, there are considerable differences from batch to batch, which is associated with batch testing required in each case, and last but not least, the extraction of serum from unborn calves is an ethical issue. METHODS: In recent years, several studies have focused on the improvement of organ culture conditions for donor corneas, including different serum-free media and alternative deswelling substances. Meanwhile, media are on the market which seem to be equivalent to serum-supplemented MEM. Nevertheless, serum-free medium has not yet found its way into routine organ culture of corneas. RESULTS: Our own preliminary studies have shown that despite the promising approaches, no satisfactory overall result could be achieved. Since only maintenance metabolism is required for storage of corneas until transplantation, in principle cultivation in the conventionally used medium seems possible without addition of serum at all. Corneas stored in this way had comparably endothelial cell density (ECD) to their counterpart stored in serum-supplemented medium. However, during the final evaluation after deswelling, the ECD dropped drastically.Engelmann et al. started research on the use of serum-free culture medium (SFM) for a long time and comparable or even superior ECD and viability could be demonstrated. So far, however, it has not been possible to define a deswelling medium adapted to these conditions.Also, a serum-free storage medium developed by Eurobio (CorneaSyn) could not completely convince, because although ECD of the examined corneas remained constant, the morphology of the cells changed. CONCLUSION: Since it is essential to intensify efforts towards a serum-free system it is planned to test serum substitutes and, if possible, also to replace the de-swelling additive dextran with a less harmful alternative to guarantee the quality of cornea grafts in the future.

Corneal Neuro-Regenerative Effect of Transcutaneous Electrical Stimulation in Rabbit Lamellar Keratectomy Model.

Purpose: This study aimed to evaluate the effect of transcutaneous electrical stimulation (TES) on corneal nerve regeneration in rabbits injured from superficial lamellar keratectomy (SLK). Methods: New Zealand White rabbits were used in this experimental study. To induce corneal nerve damage, SLK was performed using a 7.0-mm trephine. TES was applied for 28 days after the corneal nerve injury. Corneal sensitivity, Western blotting, real-time polymerase chain reaction (PCR), and immunofluorescence were performed to observe changes in the corneal tissue. Results: In the 2-Hz and 20-Hz electrical stimulation groups, the degree of corneal wound healing increased by more than 10% compared to the control group, but no significant difference was observed. Conversely, the electrical stimulation (2-Hz or 20-Hz) group showed significantly increased corneal sensitivity compared to the control group. Western blot analysis revealed that small proline-rich protein 1A (SPRR1a), a regeneration-associated protein was significantly increased in the 2-Hz group on days 1 and 7 compared to that in the other groups. Once again, nerve regeneration in the 2-Hz group was supported by the results of PCR, in which a significant increase in the nerve growth factor (NGF) on day 1 was observed compared with the other groups. Moreover, immunofluorescence after 28 days of electrical stimulation showed significant nerve regeneration in the 2-Hz group. Conclusions: TES promoted corneal nerve regeneration in rabbit SLK model. The application of electrical stimulation of 2-Hz frequency was more effective than the 20-Hz frequency, showing potential clinical applications for corneal diseases. Translational Relevance: This study shows how application of TES to the eyes that exhibit corneal nerve damage can improve corneal nerve regeneration examined by histologic analysis.

Excimer laser-assisted phototherapeutic keratectomies combined to EDTA chelation for the treatment of calcific band keratopathy.

INTRODUCTION: Calcific band keratopathy (CBK) is a relatively common chronic corneal degeneration and various forms of treatment are mentioned in the literature. CASES DESCRIPTION: Two patients (89 and 37 yo, respectively) affected by diffuse long-standing CBK in one eye and complaining of ocular pain, foreign body sensation and decreased visual acuity are reported. An ethylenediaminetetraacetic acid (EDTA) application on the ocular surface was performed associated with a customized no-touch transepithelial phototherapeutic corneal remodeling in one patient and a standard phototherapeutic keratectomy (PTK) in the second patient. Corneal transparency progressively improved in both cases since the early follow-up visits and the cornea became clear 2 weeks after surgery. In both cases, a significant reduction of ocular discomfort was reported. CONCLUSIONS: Combining EDTA chelation and excimer laser-assisted PTK represents an useful treatment of band keratopathy even in challenging cases and may help regularize corneal surface and improve corneal clarity.

Ceratopigmentação (tatuagem corneana): utilização de técnicas combinadas para melhora estética em olhos de pacientes com opacidades corneanas / Keratopigmentation (corneal tattooing): use of combined techniques for aesthetic improvement in eyes of patients with corneal opacities

RESUMO Objetivo: Relatar, por meio de uma série de casos, a percepção de pacientes com opacidade corneana sobre a eficácia da tatuagem na melhoria estética de seus olhos, utilizando a combinação de duas técnicas. Métodos: Oito pacientes responderam a um inquérito sobre sua satisfação estética com o procedimento, o desconforto pós-operatório e o impacto social observado após a cirurgia. Resultados: Todos os pacientes consideraram-se muito satisfeitos com os resultados. Em relação ao grau de desconforto no pós-operatório, 75% disseram ter tido pouco desconforto, e 25% relataram desconforto moderado. Todos os pacientes relataram melhora significativa no bem-estar social e pessoal. Da mesma forma, todos os pacientes disseram que repetiriam o procedimento. Conclusão: A tatuagem corneana surge como um método alternativo às lentes de contato e às próteses oculares em pacientes cegos com leucomas, trazendo resultados estéticos satisfatórios, duradouros e que podem promover impactos sociais na vida desses pacientes.

ABSTRACT Objective: To report, through a case series, the perception of patients about the effectiveness of corneal tattooing in the cosmetic improvement of their eyes with leukomas, using a combination of two techniques. Methods: Eight patients answered a survey regarding their cosmetic appearance satisfaction regarding the procedure, postoperative discomfort, and social impact observed after surgery. Results: All patients considered themselves very satisfied with the cosmetic results. Regarding the degree of postoperative discomfort, 75% said they had little discomfort, while 25% reported moderate discomfort. All patients reported significant improvement in social and personal well-being. Likewise, all patients said they would repeat the procedure. Conclusion: Corneal tattooing appears as an alternative method to contact lenses and ocular prostheses in impaired eyes with leukomas, bringing satisfactory and long-lasting cosmetic improvement that can promote social impacts for these patients.

Comparison of surgically induced astigmatism between anterior and total cornea in 2.2 mm steep meridian incision cataract surgery.

BACKGROUND: This study aimed to compare surgically induced astigmatism (SIA) on the anterior and total cornea during cataract surgery through a 2.2 mm steep meridian incision. METHODS: The study included 69 left eyes of 69 patients who had undergone cataract surgery. The 69 eyes were classified into three subgroups according to the preoperative steep meridian. Following phacoemulsification, an intraocular lens was inserted into the bag. The keratometric measurements were taken 12 months postoperatively, on the anterior cornea (automated keratometer and anterior keratometry [K] from a rotating Scheimpflug camera) and total cornea (equivalent K reading [EKR] 3.0 mm, EKR 4.5 mm, total corneal refractive power (TCRP) 2.0 mm ring, TCRP 3.0 mm zone, TCRP 4.0 mm zone). The SIA was analyzed for each parameter. RESULTS: On the double-angle polar plot, the summated vector mean values of SIA determined by the automated keratometer and Scheimpflug anterior K were 0.28 diopter (axis: 177°) and 0.37 diopter (axis: 175°) in with-the-rule (WTR) astigmatism; 0.03 diopter (axis: 156°) and 0.18 diopter (axis: 177°) in oblique astigmatism; 0.15 diopter (axis: 96°) and 0.17 diopter (axis: 73°) in against-the-rule (ATR) astigmatism. The mean SIAs on the total cornea ranged from 0.31 to 0.42 diopter in WTR astigmatism; from 0.16 to 0.27 diopter in oblique astigmatism; from 0.04 to 0.11 diopter in ATR astigmatism. Mean magnitude SIA ranged from 0.41 to 0.46 diopter on anterior corneal surface and 0.50 to 0.62 diopter on total cornea. J0 and J45 of the posterior cornea showed no significant changes after cataract surgery, and the changes in J0 and J45 did not show any statistical differences between the anterior and total cornea (all p > 0.05). CONCLUSIONS: There were no differences in the summed vector mean values of SIA between the anterior cornea and the total cornea.

Advances in Understanding the Mechanism of Ophthalmic Viscosurgical Device Retention in the Anterior Chamber or on the Corneal Surface during Ocular Surgery.

Retention durability, especially in the eye, is one of the most important properties of ophthalmic viscosurgical devices (OVDs) during ocular surgery. However, the information on the physical properties of OVDs is insufficient to explain their retention durability. The purpose of this study is to clarify the mechanism of OVD retention to improve understanding of the behavior of OVDs during ocular surgery. To elucidate the mechanism of OVD retention, we have developed a new test method for measuring repulsive force. As a result, the maximum repulsive force of OVDs was positively and well correlated with the retention durability of investigated OVDs. Consequently, we demonstrated that the repulsive force could be used as an index of retention durability on the ocular surface and in the eye. We directly compared the intraocular retention durability of three OVDs (Shellgan, Viscoat, and Opegan-Hi) in ex vivo porcine eyes. Opegan-Hi was immediately removed from the anterior chamber, but Shellgan and Viscoat remained largely in the anterior chamber as determined by fluorescence imaging. These results showed that the intraocular retention behavior of OVDs was similar to their ocular surface behavior in our previous report, suggesting that retention durability is dependent on the OVD itself. The retention durability of Shellgan seemed to be higher than that of Viscoat, and the maximum repulsive force of Shellgan was 1.35-fold higher than that of Viscoat. Therefore, the repulsive force might be a useful index for assessing the difference in the retention durability between OVDs such as Shellgan and Viscoat.

TNF-α Inhibitors for the Management of Intractable Corneal Melt: Report of Three Cases and Review of the Literature.

OBJECTIVE: To report three consecutive cases with noninfectious corneal melting, whose disease progression could only be halted with tumor necrosis-α (TNF-α) inhibitor infusion, with a review of the relevant literature. MATERIALS AND METHODS: Patients with toxic epidermal necrolysis, severe alkaline burn, and Sjögren syndrome had experienced severe corneal melting following penetrating keratoplasty, Boston type 1 keratoprosthesis implantation or spontaneously, respectively. Topical autologous serum eye-drops, medroxyprogesterone, and acetylcysteine formulations; frequent nonpreserved lubrication; systemic tetracyclines and vitamin-C supplements; topical and systemic steroids and steroid-sparing agents; surgical approaches including amniotic membrane transplantation, tectonic graft surgery; and tarsorraphy failed to alter the disease courses. RESULTS: Upon consultation with the rheumatology clinic, TNF-α inhibitor infliximab (Remicade; Centocor Ortho Biotech Inc, Horsham, PA) 5 mg/kg infusion was planned for each patient. After 0-, 2-, and 6-week doses, monthly infusion at the same dose was maintained for 12 months because of severe and intractable course of their diseases. Each case showed dramatic improvements in corneal melts; and sterile vitritis in the eye with Boston keratoprosthesis responded, as well. CONCLUSIONS: Inhibiting TNF-α-mediated expression of matrix metalloproteinases responsible for collagen breakdown should be considered in refractory cases, as a means of globe salvage.

Successful management of epithelial ingrowth after sequential intracameral 5-fluorouracil and Descemet-stripping automated endothelial keratoplasty.

To describe the successful treatment of epithelial ingrowth using combined surgical excision with intracameral adjuvant 5-fluorouracil (5-FU) followed by Descemet-stripping automated endothelial keratoplasty (DSAEK). A 71-year-old man presented with epithelial ingrowth after clear corneal phacoemulsification. He underwent surgical excision of the membrane together with pars plana vitrectomy, air fluid exchange, and intracameral 5-FU. This treatment resulted in corneal decompensation for which DSAEK was performed 6 months later. Despite interface haze, the postoperative corrected distance visual acuity returned to 20/40 three months after DSAEK. There was no clinical evidence of recurrence of the epithelial ingrowth 9 months after the surgical removal. Intracameral 5-FU can be used in conjunction with surgical excision and subsequent DSAEK to successfully treat epithelial ingrowth.

Early post-LASIK flap amputation in the treatment of aggressive, branching keratitis: a case report.

Infectious keratitis is rare following laser vision correction. We present a case of aggressive fungal keratitis caused by Aspergillus flavus, following laser in situ keratomileusis (LASIK) in the setting of a unique environmental risk factor. We describe the key features of the acute case presentation, which guided empirical medical and surgical treatment, resulting in the most favorable outcome found in the literature, to date.

Early post-LASIK flap amputation in the treatment of aggressive, branching keratitis: a case report / Amputação precoce de pedículo de LASIK para o tratamento de ceratite ramificada agressiva: relato de caso

ABSTRACT Infectious keratitis is rare following laser vision correction. We present a case of aggressive fungal keratitis caused by Aspergillus flavus, following laser in situ keratomileusis (LASIK) in the setting of a unique environmental risk factor. We describe the key features of the acute case presentation, which guided empirical medical and surgical treatment, resulting in the most favorable outcome found in the literature, to date.

RESUMO Ceratites infecciosas são raras após a correção da visão a laser. Apresentamos um relato de caso de uma ceratite fúngica agressivo por Aspergillus flavus, após ceratomileuse a laser "in situ" (LASIK) em situação peculiar de fator de risco ambiental. Nós descrevemos as principais características da apresentação caso agudo, que orientou tratamento médico e cirúrgico empírico, demonstrando resultado mais favorável do que o encontrado na literatura até o momento.

Anterior Synechiolysis with Healon Needle and Ophthalmic Viscosurgical Devices after Anterior Lamellar Dissection in Penetrating Keratoplasty.

PURPOSE: We described a technique to perform anterior synechiolysis with a healon needle and Viscoat® ophthalmic viscosurgical devices (OVDs) through anterior lamellar dissection in penetrating keratoplasty. METHODS: OVDs were gently injected between iridocorneal adhesions with a healon needle to make a blunt dissection after anterior lamellar corneal dissection. Anterior synechiolysis at 360 degrees was completed with a healon needle and OVDs. Subsequently, the deep corneal lamella was cut with right and left Troutman-Katzin corneal scissors. 24 interrupted sutures were made with 10-0 nylon suture to implant the donor cornea. RESULTS: In two eyes from two patients, with corneal opacity and nearly total anterior synechiae, clear grafts and relatively deep anterior chambers were achieved. Penetrating keratoplasty with anterior synechiolysis was thus successful with a healon needle and OVDs through lamellar dissection. CONCLUSIONS: Anterior synechiolysis with a healon needle and OVDs through lamellar dissection is a safe and efficient technique for keratoplasty in patients with corneal opacity with anterior synechiae.

Effect of onion extract on corneal haze suppression after air assisted lamellar keratectomy.

This study evaluated the effect of onion extract on corneal haze suppression after applying the air assisted lamellar keratectomy. The air assisted lamellar keratectomy was performed on 24 canine eyes. They were treated with an artificial tear (group C), prednisolone acetate (group P), onion extract (group O) and TGF-ß1 (group T) three times per day from 7 to 28 days after the surgery. Corneal haze occurred on the all eyes and was observed beginning 7 days after the surgery. The haze was significantly decreased in groups P and O from day 14 compared with the group C using the clinical (group P; P=0.021, group O; P=0.037) and objective evaluation method (group P; P=0.021, group O; P=0.039). In contrast, it was significantly increased in group T from day 14 compared with group C based on the clinical (P=0.002) and objective evaluation method (P<0.001). Subsequently, these eyes were enucleated after euthanasia, and immunohistochemistry with α-SMA antibodies was done. The total green intensity for α-SMA was significantly more expressed in group T and significantly less expressed in groups P and O than in group C. Onion extract could have potential as a therapeutic in preventing corneal haze development by suppressing the differentiation of fibroblasts into myofibroblasts.

Detachable microsphere scalpel tips for potential use in ophthalmic surgery with the erbium:YAG laser.

Vitreoretinal surgery is performed using mechanical dissection that sometimes results in iatrogenic complications, including vitreous hemorrhage, retinal breaks, incomplete membrane delamination, retinal distortion, microscopic damage, etc. An ultraprecise laser probe would be an ideal tool for cutting away pathologic membranes; however, the depth of surgery should be precisely controlled to protect the sensitive underlying retina. The ultraprecise surgical microprobe formed by chains of dielectric spheres for use with the erbium:YAG laser source (λ=2940 nm), with extremely short optical penetration depth in tissue, was optimized. Numerical modeling demonstrated a potential advantage of five-sphere focusing chains of sapphire spheres with index n=1.71 for ablating the tissue with self-limited depth around 10 to 20 µm. Novel detachable microsphere scalpel tips formed by chains of 300 µm sapphire (or ruby) spheres were tested on ophthalmic tissues, ex vivo. Detachable scalpel tips could allow for reusability of expensive mid-infrared trunk fibers between procedures, and offer more surgical customization by interchanging various scalpel tip configurations. An innovative method for aiming beam integration into the microsphere scalpel to improve the illumination of the surgical site was also shown. Single Er:YAG pulses of 0.2 mJ and 75-µs duration produced ablation craters in cornea epithelium for one, three, and five sphere structures with the latter generating the smallest crater depth (10 µm) with the least amount of thermal damage depth (30 µm). Detachable microsphere laser scalpel tips may allow surgeons better precision and safety compared to mechanical scalpels when operating on delicate or sensitive areas like the retina.

Epithelial wound healing after cataract surgery comparing two different topical fluoroquinolones.

PURPOSE: To compare the epithelial wound healing response of two preservative-free fluoroquinolones, moxifloxacin and levofloxacin, in patients who underwent cataract surgery. MATERIALS AND METHODS: In this prospective, evaluator-masked, randomized clinical trial, 59 eyes of 50 patients who underwent cataract surgery were enrolled. Patients were randomized to receive moxifloxacin 0.5% (n=32 eyes) or levofloxacin 0.5% (n=27 eyes). All patients instilled moxifloxacin or levofloxain four times daily for 1 week prior to surgery and 2 weeks after surgery. The epithelial wound healing status in the corneal incision site was scanned with a raster scan mode of fourier-domain optical coherence tomography (FD-OCT). The number of eyes showing epithelial defect images and average number of corneal epithelial defect cuts per eye were compared between groups. All patients were evaluated on postoperative days 1, 2, 3, and 10. RESULTS: On postoperative days 1, 2, and 3, the number of eyes showing epithelial defects in FD-OCT was not statistically different (all p>0.05). The average number of corneal epithelial defect cuts was also not statistically different between the two groups (all p>0.05). No eyes showed epithelial defects on postoperative day 10 in either group. CONCLUSION: There were no differences on epithelial wound healing comparing these two different fluoroquinolones at the incision site of cataract surgery.

Degree and duration of corneal anesthesia after topical application of 0.4% oxybuprocaine hydrochloride ophthalmic solution in ophthalmically normal dogs.

OBJECTIVE: To assess the anesthetic efficacy and local tolerance of topically applied 0.4% oxybuprocaine ophthalmic solution to in dogs and compare its effects with those of 1% tetracaine solution. ANIMALS: 34 ophthalmically normal Beagles. PROCEDURES: Dogs were assigned to 2 groups, and baseline corneal touch threshold (CTT) was measured bilaterally with a Cochet-Bonnet aesthesiometer. Dogs of group 1 (n = 22) received a single drop of 0.4% oxybuprocaine ophthalmic solution in one eye and saline (0.9% NaCl) solution (control treatment) in the contralateral eye. Dogs of group 2 (n = 12) received a single drop of 0.4% oxybuprocaine ophthalmic solution in one eye and 1% tetracaine ophthalmic solution in the contralateral eye. The CTT of each eye was measured 1 and 5 minutes after topical application and then at 5-minute intervals until 75 minutes after topical application. RESULTS: CTT changes over time differed significantly between oxybuprocaine-treated and control eyes. After instillation of oxybuprocaine, maximal corneal anesthesia (CTT = 0) was achieved within 1 minute, and CTT was significantly decreased from 1 to 45 minutes, compared with the baseline value. No significant difference in onset, depth, and duration of corneal anesthesia was found between oxybuprocaine-treated and tetracaine-treated eyes. Conjunctival hyperemia and chemosis were detected more frequently in tetracaine-treated eyes than in oxybuprocaine-treated eyes. CONCLUSIONS AND CLINICAL RELEVANCE: Topical application of oxybuprocaine and tetracaine similarly reduced corneal sensitivity in dogs, but oxybuprocaine was less irritating to the conjunctiva than was tetracaine.

[Therapeutic excimer laser treatment of the cornea]. / Therapeutische Excimerlaserchirurgie der Hornhaut.

Concomitant with new innovations in the field of refractive surgery, therapeutic excimer laser applications like phototherapeutic keratectomy (PTK) and topography-guided customised ablation treatment are gaining high importance and undergoing rapid evolution. Nowadays, PTK is an effective treatment modality for superficial corneal pathologies. Primary indications are decreased epithelial adherence, superficial opacifications and an irregular corneal surface. For the right indication and successful treatment of corneal pathologies with PTK, a knowledge of the size, depth and nature of the pathology, as well as the refractive status of both eyes is important. Next to slit-lamp examination, objective measuring systems like the topography, confocal microscopy and the anterior segment OCT facilitate presurgical planning. Regarding the treatment procedure the surgeon can choose between a variety of methods. PTK can be combined with manual epithelial debridement or done by only using the excimer laser. In the case of an irregular corneal surface, depending on the pathology, masking fluids or topography-guided custom ablation protocols can increase the visual outcome. To avoid recurrence of the underlying pathology (e.g., corneal dystrophy, haze), the topical application of 0.02% mitomycin C for 20-60 seconds has proved to be a safe and effective procedure. If the surgeon considers all the patient-related factors carefully and manages to combine the available treatment options correctly, PTK embodies an effective and minimally invasive alternative to lamellar or penetrating keratoplasty.

Use of a calibrated force gauge in clear corneal cataract surgery to quantify point-pressure manipulation.

PURPOSE: To develop and evaluate a calibrated force gauge designed to simulate the effect of patient-induced manipulation of the eye with resultant elevation of intraocular pressure (IOP) and use the device to determine the stability of cataract incisions. SETTING: Three private practice study sites. DESIGN: Clinical trials. METHODS: A calibrated force gauge was developed to apply controlled and quantifiable amounts of force to the eye. In study 1, the calibrated force gauge was used to evaluate the change in IOP during application of 1 oz of external force in a group of healthy volunteers. In studies 2 and 3, the calibrated force gauge was used to assess wound leakage of clear corneal incisions that were subjected to stromal hydration or sutures, respectively. RESULTS: In study 1, with the application of 1.00 oz of external force, the mean IOP rose from a baseline of 17.49 mm Hg to 43.44 mm Hg. In study 2 (stromal hydration) using up to 1.00 oz of force, the leak rate was 67% for the main incision. The overall leak rate for study 3 (sutures) using up to 1.00 oz of force was 23.8%. No adverse events or serious adverse events occurred during these studies. CONCLUSIONS: Study 1 confirmed that 1.00 oz of force is a realistic approximation of the amount of force a patient's eye may experience during rubbing. After clear corneal cataract surgery, the application of 1.00 oz of force to the ocular surface for approximately 2 to 3 seconds may simulate the propensity for postoperative wound leak resulting from patient manipulation.