Microkeratome Blade Research Articles

Preferred cataract surgery practices in Malaysia: a survey based study

BackgroundTo describe the preferred cataract surgery practices among Malaysian ophthalmologists and medical officers in comparison with the recommended practices.MethodsAn online questionnaire was sent out in April 2021, to Malaysian Ophthalmologists and medical officers who perform cataract surgeries. The questions were focused on the preferred cataract surgery practices of the participants. All data obtained were collected, tabulated and analysed.ResultsA total of 173 participants responded to the online questionnaire. 55% of the participants were within 31–40 years of age. 56.1% preferred peristaltic pump over venturi system. 91.3% of participants practised povidone iodine instillation to the conjunctival sac. With regards to the main wound incision, more than half of the surgeons (50.3%) preferred fixed superior incision and 72.3% of them preferred 2.75 mm microkeratome blade. Most of the participants (63%) were inclined towards C-Loop clear intraocular lens (IOL) with a single-handed push preloaded system. 78.6% of the surgeons routinely use carbachol in their cataract surgery.ConclusionsThis survey provides some insight into the current practices among Malaysian ophthalmologists. Most of the practices are in line with international guidelines for preventing postoperative endophthalmitis. This article could help trainees and ophthalmologists benchmark and observe the common cataract surgery practices among their seniors and peers in Malaysia.

Nomogram for single-pass automated microkeratome graft preparation for ultrathin Descemet stripping automated endothelial keratoplasty.

To create a nomogram including the translational speed of the microkeratome blade, microkeratome head size and precut tissue thickness to predict the postcut thickness for Descemet stripping automated endothelial keratoplasty to obtain the thinnest possible graft. This prospective study incorporated 48 grafts for DSAEK from March 2017 to June 2020. Corneal tissue for DSAEK was prepared by 3 experienced physicians using the Moria Evolution 3E (Moria Inc, Antony, France) microkeratome with 400, 450 and 500μm head sizes. Precut central corneal thickness was measured with a DGH 550 handheld pachymeter (Pachette 2), taking an average of 3 readings. The microkeratome head was selected according to precut tissue thickness. The selected microkeratome head size was 150μm less than the donor cornea thickness. Two translational speeds were used for the microkeratome cuts. One month after surgery, the central lenticular thickness was measured with a Visante® Optical Coherence Tomography caliper (Carl Zeiss Meditec Inc, Germany). A descriptive analysis was performed. Forty-eight donor grafts were prepared. Mean graft thickness was 97.58 ± 29.84μm (range 39-176μm). Of the 48 samples, central graft thickness was < 120µm (81.3%) in 39, < 100µm (58.3%) in 28 and < 80µm (37.5%) in 18 at 1-month follow-up. There were no statically significant differences between translational speeds. A nomogram with an automated microkeratome to obtain thin grafts for DSAEK provided good graft thickness results without donor waste.

Short term changes in corneal stress-strain index and other corneal biomechanical parameters post-laser in situ keratomileusis

Purpose:To report the short-term changes in a corneal stress-strain index (SSI) and other corneal biomechanical parameters post-laser in situ keratomileusis (LASIK) surgery.Methods:A retrospective study was conducted at a tertiary eye care center wherein patients who had undergone LASIK (microkeratome blade and femtosecond bladeless LASIK) between July and December 2019 were enrolled. Patients of age group 20–40 years, best-corrected visual acuity of 20/20, intraocular pressure (IOP) <22 mmHg, pre-LASIK pachymetry >500 microns, and corneal astigmatism ≤3.00 D were included. Subjects with a prior history of refractive surgery, any other ocular or systemic disease, poor-quality scans, intraoperative complications, and missing data were excluded. Corneal biomechanical properties including SSI were analyzed using Corvis ST and compared using the Paired T-test for each group separately at pre-LASIK, and 1-month post-operatively.Results:Overall, 202 eyes were reviewed, and 79 eyes fulfilled the inclusion criteria. Forty-three and 36 eyes had undergone Microkeratome Blade LASIK (Group I) and Femto LASIK (Group II), respectively. Overall, 29 and 26 corneal biomechanical parameters out of 33 changed significantly post-Microkeratome Blade LASIK and Femto LASIK, respectively. Statistically significant changes were noted in all the parameters at A1, maximum and Vinciguerra screening parameters (P < 0.001), however, no changes were noted in SSI in both the groups when compared with the pre-surgery data.Conclusion:Though the reduction in SSI was not statistically significant, other biomechanical parameters showed significant biomechanical changes pre- and post-LASIK surgeries in both the groups. However, a long-term study with a larger sample size would be required to understand the changes and stability in SSI post-refractive surgery.

DSAEK

The aim of this study was to supply data on the relationship between Descemet stripping automated endothelial keratoplasty (DSAEK) graft thickness and its effects on visual acuity (VA), pace of visual recovery, endothelial cell densities (ECDs), and surgical complications. We additionally provide an approach for choosing the microkeratome blade thickness when multiple patients are scheduled for DSAEK. This is a retrospective analysis of all DSAEK procedures performed at our institute from January 2011 to December 2012. The VA was assessed at all postop visits. The ECD was assessed at 6 and 12 months postoperatively. An algorithm based on donor cornea pachymetry was used to assist in the choice of a microkeratome blade either 350 or 400 μm thick. Two groups were created on the basis of the microkeratome blade chosen. Outcomes were given per treatment group. One hundred two consecutive DSAEK procedures were performed; 60 grafts were prepared with the 350-μm blade and 39 with the 400-μm blade. Baseline characteristics did not differ materially. Grafts dissected using the 350-μm knife were significantly thicker than the grafts dissected with the 400-μm blade, with values of 257 ± 47 μm and 222 ± 33 μm, respectively (P = 0.01). The pace of visual recovery, VA at maximum follow-up, and ECD did not differ significantly between groups. Surgical complications were evenly distributed over both groups. This study indicates that using neither the 350-μm nor 400-μm microkeratome blade for the DSAEK altered the outcomes in terms of VA, ECD, and surgical complications. The algorithm presented in this study is helpful in equally distributing benefits from thinner grafting for all DSAEK-operated patients.

Textural Interface Opacity After Descemet Stripping Automated Endothelial Keratoplasty

Descemet stripping automated endothelial keratoplasty (DSAEK) has its own set of complications including interface abnormalities. This case series presents the largest number of patients who developed textural interface opacity (TIO) at the graft-host interface after DSAEK. This is a retrospective multicenter case series of 30 patients from 7 institutions with the finding of TIO. Clinical information collected included donor preparation details, recipient information, and surgical technique. Clinical outcomes included best-corrected visual acuity and status of TIO appearance at the last follow-up visit. Slit-lamp photographs were analyzed and compared. The majority of the patients (73%) had a best-corrected visual acuity of 20/40 or better. Four of the donor tissues were prepared with a microkeratome blade with the same lot number. Six patients had a central interface space between host and donor stromal surfaces--presumed interface fluid but potentially viscoelastic. A slight majority (57%) of patients had improvement in the severity of TIO, with 20% noted to have a complete resolution of TIO (mean follow-up of 11.9 months). Two clinical types of TIO were seen: an elongated type and a punctate type. Most patients with TIO after DSAEK obtain good visual outcomes. TIO spontaneously improves or even resolves during follow-up without intervention. The etiology of this condition is unknown, but we propose 2 different mechanisms. The elongated type could be secondary to an irregular cut of the donor with the microkeratome blade. The punctate type may be secondary to retained viscoelastic.

Corneal Donor Tissue Preparation for Endothelial Keratoplasty

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection3-6.Initially, cornea donor posterior lamellar dissection for DSEK was performed manually1 resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing.Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in terms of the quality of the tissue7 or patient outcomes8,9 using eye bank precut tissue versus surgeon-prepared tissue for DSAEK surgery. For most corneal surgeons, the availability of precut DSAEK corneal tissue saves time and money10, and reduces the stress of performing the donor corneal dissection in the operating room. In part because of the ability of the eye banks to provide high quality posterior lamellar corneal in a timely manner, DSAEK has become the standard of care for surgical management of corneal endothelial disease.The procedure that we are describing is the preparation of the posterior lamellar cornea at the eye bank for transplantation in DSAEK surgery (Figure 1).

Corneal Donor Tissue Preparation for Endothelial Keratoplasty

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection3-6. Initially, cornea donor posterior lamellar dissection for DSEK was performed manually1 resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing. Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in terms of the quality of the tissue7 or patient outcomes8,9 using eye bank precut tissue versus surgeon-prepared tissue for DSAEK surgery. For most corneal surgeons, the availability of precut DSAEK corneal tissue saves time and money10, and reduces the stress of performing the donor corneal dissection in the operating room. In part because of the ability of the eye banks to provide high quality posterior lamellar corneal in a timely manner, DSAEK has become the standard of care for surgical management of corneal endothelial disease. The procedure that we are describing is the preparation of the posterior lamellar cornea at the eye bank for transplantation in DSAEK surgery (Figure 1).

The investigation of microbial culturing of microkeratome blades and sponges used in laser in situ keratomileusis

The microbial culturing results were analysed from samples of the microkeratome blade and sponges in laser in situ keratomileusis (LASIK) procedures as for crossing the rational antibiotic eye drops for preventing infectious keratitis. In this prospective study, 106 microkeratome blades and 212 sponges were cultured in routine LASIK procedure, at Excimer laser center in Henan Eye Institute During March to April 2009. Positive cultures were then sent for routine sensitivities and the results were analysed. 8 of the 106 blades were culturing positive, the positive rate was 7.55%. Each four positive cultures were in male and female patients. There was no statistical difference with gender (P = 1.000). 23 of the 212 sponges cultures were positive. The positive rate was 10.38%. All positive cultures grew Staphylococcus epidermidis. Twelve sponge positive cultures were in right eye and 11 were in left eye. There was no statistical difference between the right eye and left eye (P = 0.825). All of the 31 positive cultures were sensitive to gatifloxacin. The sensitivity of gatifloxacin, tobramycin, levofloxacin, ofloxacin, and ciprofloxacin were 100.00%, 96.77% (30/31), 93.55% (29/31), 90.32% (28/31) and 74.20% (23/31) respectively. All the patients have no infectious keratitis followed-up more then 6 monthes. There could be positive cultures from samples of the microkeratome blade and sponges in routine LASIK procedures but no patients with positive cultures developed postoperative infectious keratitis. The main positive bacteria was Staphylococcus epidermidis. They are sensitive to third and the fourth-generation fluoroquinolones and tobramycin antibiotics. Pre and post-operative supply of sensitive antibiotics can prevent post-operative infection.

Flap Buttonhole in Thin-Flap Laser In Situ Keratomileusis: Case Series and Review

To analyze the clinical features and the risk factors leading to formation of flap buttonhole during laser in situ keratomileusis (LASIK) and the postablation visual outcome. Medical records of all eyes that developed flap buttonhole during LASIK were retrospectively reviewed. Pre-LASIK measurements and intraoperative parameters were analyzed to predict the risk factors. A total of 944 eyes underwent LASIK during the study duration. Four eyes (0.42%) developed partial thickness flap buttonhole. Thin-flap LASIK (flap thickness < or =90 microm) was performed in 230 eyes. The incidence of buttonholes in thin-flap LASIK cases was 1.7% (4 of 230). LASIK procedures were performed at a tertiary eye institute between October 2006 and December 2008. The mean age was 31 +/- 8.7 years. Preablation mean spherical refractive error in the affected left eye was -7.8 +/- 1.2 diopters (D), mean steeper axis keratometry was 44.0 +/- 1.56 D, and the mean pachymetry was 520 +/- 16 microm. Buttonholing in the flap occurred in the second (left) eye of all 4 cases. All cases had undergone thin-flap LASIK with 90-microm blade using the Moria M2 microkeratome. Flap diameter was +2/7.5 and 0/8.0 for 2 eyes each. Twelve weeks after the initial procedure, transepithelial phototherapeutic keratectomy/photorefractive keratectomy was performed in all 4 eyes. Postablation visual outcome was 20/20 and 20/25 in 2 eyes each. One patient had a faint subepithelial scar at the last 1-year follow-up. Formation of flap buttonhole is significantly more common in the second eye and with the usage of Moria M2 microkeratome and 90-microm blade. In thin-flap LASIK, the practice of using the same microkeratome blade for the fellow eye, as is commonly followed at many refractive surgery centres, should be abandoned. Intraoperative subtraction pachymetry may be helpful in predicting the risk of buttonhole in the second eye. These precautions are especially mandatory in thin-flap LASIK irrespective of the other associated risk factors.

Effect of varying microkeratome parameters on laser in situ keratomileusis interface surfaces

To evaluate the effect of altering microkeratome parameters (oscillation rates and head-advance speeds) and repeated blade use on human and porcine laser in situ keratomileusis interface surface quality and to evaluate correlations between human and porcine interface surface quality. Emory Vision, Atlanta, Georgia, USA. Corneal flaps were created in porcine eyes and human cadaver eyes with an Amadeus I microkeratome using varying head-advance speeds and oscillation rates. Microkeratome blades were used once in 18 porcine eyes, twice in 18 human eyes (simulating clinical use), and 5 times in 15 porcine eyes. The interface surface was imaged with electron microscopy, with overall bed quality and surface smoothness graded from 1 to 5 (smoothest to roughest) by 5 masked corneal specialists using the same grading criteria for porcine eyes and human eyes. Neither oscillation rates nor head-advance speeds consistently influenced bed smoothness in any group. There were no differences in bed quality between first cuts and second cuts in human eyes or between porcine eyes with multiple blade use. Porcine eyes had statistically significantly smoother stromal beds than human eyes (P<.01); there was no correlation between porcine eye scores and human eye scores (r = -0.1). Neither alterations in microkeratome parameters nor repeated blade use consistently influenced stromal bed quality in human or porcine eyes. No subjective correlation existed between stromal bed qualities of porcine corneas and human corneas; therefore, future studies evaluating corneal stromal bed quality should be performed in human corneas only.

Amadeus® II Microkeratome: Optimizing Microkeratome Settings for High Flap Accuracy Using Optical Low Coherence Reflectometry

To investigate the impact of various experimental microkeratome settings and blade reuse on the accuracy of the flap thickness created with the new Amadeus II microkeratome (SIS, Ziemer Ophthalmic, Port, Switzerland). In this prospective study, 120 porcine eyes were used to create corneal flaps with the Amadeus II using 2 different cutting heads (140 microm, 160 microm) with the Surepass blade. Using each blade twice, a head advance speed of 1.5 mm/s and 3.5 mm/s and oscillation rates of 8000 rpm, 10,000 rpm, and 13,000 rpm were used. Flap thickness was measured by optical low coherence reflectometry (OLCR). Descriptive statistical analysis was based on means, medians, and quartiles, with graphical representation on box plot. Pearson correlation test and Mann-Whitney U-test for unpaired samples were employed to identify the impact of different settings. Using the 140 microm cutting head, highest precision of the flap thickness was achieved with a head advance rate of 1.5 mm/s and an oscillation rate of 10,000 rpm (mean 132.1+/-10.0 microm; range 120.2-147.2 microm). Reusing the blade, highest accuracy (mean 130+/-6.9 microm; range 118.5-135 microm) was achieved with 8000 rpm. Using the 160 microm cutting head, an optimum flap thickness was reached with a head advance rate of 3.5 mm/s and an oscillation rate of 13,000 rpm (mean 162.4+/-7.7 microm; range 151.9-169.8 microm). Reusing the blade with the 160 microm cutting head, an adjustment to 3.5 mm/s and 10,000 rpm was necessary (mean 157.4+/-7.7 microm; range 153.7-161.8 microm). Optimized microkeratome settings lead to minimized deviation from the intended flap thickness and are mandatory to improve flap accuracy. OLCR is an ideal method to proof individualized settings.

Corneal flap thickness with the Moria M2™ microkeratome and Med‐Logics calibrated LASIK blades

This study aimed to compare and study potential factors that affect the accuracy of corneal flap thickness created in laser-assisted in situ keratomileusis (LASIK) using the Moria model 2 (M2) head 130 microkeratome with the Med-Logics calibrated LASIK blades Minus 20 (ML -20) and Minus 30 (ML -30). Corneal thickness in 200 (164 myopic and 36 hyperopic) eyes (100 patients) was measured by ultrasonic pachymetry preoperatively and intraoperatively after flap cutting. A total of 100 eyes were treated with the ML -20 and 100 with the ML -30. The right eye was operated before the left eye in each patient, using the same blade. In an additional group of 40 eyes, the left eye was operated first. Mean corneal flap thickness using the ML -20 blade for an intended flap thickness of 140 μm was 129.1 μm (standard deviation [SD] 15.6, range 104-165 μm) in right eyes and 111.5 μm (SD 14.5, range 78-144 μm) in left eyes. Mean corneal flap thickness using the ML -30 blade for an intended flap thickness of 130 μm was 127.1 μm (SD 16.6, range 90-168 μm) in right eyes and 109.9 μm (SD 16.8, range 72-149 μm) in left eyes. Both microkeratome blade types cut thinner flaps than were intended. There was substantial variation in flap thickness. The first flap to be cut with a particular blade was considerably thicker than the second flap cut with the same blade. Based on these data, we recommend the use of disposable single-use microkeratomes rather than these ML blades.

Pre-cut donor tissue for Descemet stripping automated keratoplasty: anterior hinged lamella on versus off

AimsTo compare two different techniques for preparation of pre-cut lamellar corneal tissue for Descemet stripping automated keratoplasty.Background/MethodsEight donor lenticules were created with a full pass of the microkeratome blade, which...

A new storage medium for pre‐cut donor tissue for DSAEK in eye bank

Abstract Purpose To evaluate the efficacy of a new storage medium able to avoid swelling the donor cornea before the microkeratome cut in eye bank routine setting Methods The Eusol‐C (Alchimia s.r.l.,Italy) storage medium and a modified storage medium (only for experimental use,Alchimia) were used to store two different sets of donor corneas (n=12).Before the microkeratome cut,corneas were stored in Eusol‐C (n=6) while the controlateral donor corneas were stored in the modified medium (M.M.) (n=6).Donor lenticules were created with a full pass of microkeratome blade which resulted in a posterior lamella and a free cap.Endothelial cell density,cellular viability and corneal thickness by AS‐OCT (VisanteTM,Carl Zeiss) were evaluated before dissection,4,24 and 48 hours after dissection. Results Endothelial cell density and cellular viability were well preserved during the time course in both storage medium.Pachymetry values, after the microkeratome cut did not show significant variations during the time course.Conversely significant differences were found between the two groups (p&lt;0,05).Average corneal thickness immediately before dissection was 659+/‐38,08 microns and 537,83+/‐24,78 microns in Eusol‐C and in M.M. respectively.Immediately after dissection, thickness of the residual posterior bed was 247,83+44,13 (Eusol‐C)and 143,6+24,96(M.M.)microns.After 4, 24 and 48 hours was 238,5+41; 238,83+42,73 and 232,83+39,01 microns respectively in Eusol‐C.Instead in M.M. after 4, 24 and 48 hours was 141,2+24,92;145,6+22,35 and 157,2+30,40 microns respectively.The M.M. was able to reduce,on the controlateral corneas,the thickness of 100 microns in average. Conclusion The M.M.was capable of preventing corneal tissue swelling during storage of pre‐cut tissue for DSAEK.

Microbial cultures of the microkeratome blade immediately after flap construction in laser in situ keratomileusis

To assess the incidence of positive cultures from samples of the microkeratome blade after routine laser in situ keratomileusis (LASIK) procedures as a measure of the risk for postoperative infectious keratitis. Hinsdale Surgical Center, Hinsdale, Illinois, USA. In this prospective study, 99 microkeratome blades (Hansatome) were cultured after routine LASIK procedures by multiple surgeons at an ambulatory surgery center. Cultures were sent for routine aerobic and anaerobic growth. Positive cultures were then sent for routine sensitivities. Five of 99 swabs of microkeratome blades were culture positive. Four cultures grew Staphylococcus epidermidis and 1, Staphylococcus warneri. Two of the staphylococcal cultures were resistant to ciprofloxacin and levofloxacin but sensitive to moxifloxacin and gatifloxacin. The study demonstrated a 5% positive culture rate from the microkeratome blade after routine LASIK surgery by multiple surgeons in an ambulatory surgery center. No patient with positive cultures developed postoperative infectious keratitis. Factors other than the presence of bacteria contribute to the development of clinical infection.

Comparison of corneal flap thickness between primary eyes and fellow eyes using the Zyoptix XP microkeratome

To evaluate corneal flap thickness created in myopic laser in situ keratomileusis (LASIK) using the Zyoptix XP 120 microkeratome (Bausch & Lomb). University-based eye clinic. Corneal thickness was measured preoperatively and intraoperatively after flap creation in 62 consecutive patients (124 eyes) who had LASIK for the correction of myopia. Corneal flap thickness was calculated by subtracting stromal bed thickness from total corneal thickness. In each patient, both corneas (right followed by left) were cut by 1 the same Zyoptix XP 120 microkeratome blade at the same session. The mean actual flap thickness was 115.34 microm +/- 16.34 (SD) in right eyes and 104.55 +/- 14.34 mum in left eyes. The mean actual flap thickness in right eyes was not statistically significantly different from the 120 microm proposed by the manufacturer (P = .142); however, the mean actual flap thickness in left eyes was statistically significantly different from the 120 microm (P<.001). The mean flap thickness in the second eye was also statistically significantly thinner than in the first eye (P<.001). The corneal flaps were thinner than expected when a Zyoptix XP 120 microkeratome was used in LASIK. Although the first cuts produced thinner flaps, this difference was not statistically significant. However, the second cuts produced significantly thinner flaps.

Microkeratome-assisted phacoemulsification

This study reports a technique in which phacoemulsification and intraocular lens (IOL) insertion are performed in conjunction with a microkeratome flap in a patient with ocular surface disease. Microkeratome-assisted phacoemulsification was performed in a 72-year-old woman with a history of trachoma during childhood. A 130 microm corneal flap was made using a microkeratome prior to phacoemulsification and IOL insertion. Lifting the flap during surgery allowed a clear view of the anterior chamber through the smooth lamellar interface created by the microkeratome blade. The flap was washed and repositioned without sutures at the end of surgery. There were no complications associated with the microkeratome flap following surgery. Visual acuity improved from hand motion to 20/200. Microkeratome-assisted phacoemulsification is a safe technique for cataract patients with diseases of the ocular surface.

Observation of the corneal flap interface with metal particles in a rabbit model

To observe changes, such as diffuse lamellar keratitis, at the corneal interface when metal particles from microkeratome blades were left in rabbit eyes. Department of Ophthalmology, Tokyo Dental College, Suidobashi Hospital, Tokyo, Japan. Following the creation of a corneal flap with microkeratome, metal particles from a microkeratome blade were placed at the corneal interface in 14 rabbit eyes. Microscopic and histopathologic changes were compared with those in the control eyes (n = 4), which did not receive any metal particles. Each examination was conducted at 3 days, 2 weeks, and 1 and 3 months postoperatively. The change in the depth of the metal particles was also measured. Slitlamp examination did not show an inflammatory reaction or corneal opacification in any eye (100%) with metal particles at the flap interfaces. Histopathologic examinations showed no obvious changes at the flap interfaces or around the metal particles in any eye. Inflammatory reactions, such as diffuse lamellar keratitis, do not appear to be induced by metal particles from the microkeratome blade itself.

Plastic particles at the LASIK interface

Purpose To investigate the origin, composition, and persistence of the interface particles that frequently are observed after LASIK. Design Small case series and experimental animal study. Methods Four patients received LASIK using a Schwind Supratome (Schwind, Kleinostheim, Germany) and a MEL 70 G-Scan excimer laser (Asclepion, Jena, Germany) and were examined over the course of 1 year using slit-lamp and in vivo confocal microscopy. Four rabbits received a monocular microkeratome incision and were examined immediately after surgery without lifting the flap. After monthly evaluation for 4 months using in vivo confocal microscopy, 2 corneas were processed for histologic analysis and were sectioned serially. To measure the iron content, atomic absorption spectrometry was performed on 2 operated and 2 unoperated rabbit corneas. The chemical composition of the metal and plastic parts of the microkeratome blade was identified using energy dispersive x-ray fluorescence (metal part), and Raman and infrared spectroscopy (plastic part). Before and after oscillation in air, the microkeratome blade and motor-head were examined using light and fluorescence microscopy. In serial sections, interface particles were identified by fluorescence microscopy and their chemical composition was determined using Coherent Antistokes Raman Scattering microscopy. Results In LASIK patients, thousands of brightly reflecting particles (up to 30 μm) were observed throughout the interface. The highest particle density was detected where the microkeratome blade had first entered the cornea. Both in the center and at the flap edge, the morphologic features, distribution, and density of these particles remained unaltered throughout the 1-year observation period. In rabbit corneas, interface particles were observed immediately after the microkeratome incision, even though the flap had not been lifted. These particles were similar to those observed in humans and persisted unaltered throughout the study. The operated and unoperated rabbit corneas had comparable iron content, demonstrating that the particles were not fragments of the uncoated steel blade. Only a few particles were observed on the unused microkeratome motor head and blade, whereas numerous fluorescent particles were detected after oscillation in air, the amount of particles increasing with oscillation time. Interestingly, the only fluorescent part of the microkeratome was the plastic segment of the blade. This plastic (polyetherimide) emitted fluorescence identical to that of the observed particles, whereas all metal parts of the microkeratome blade and motor head were nonfluorescent. In serial sections, interface particles showed fluorescent properties equivalent to polyetherimide and exhibited molecular resonance at 1780 and 3100 cm −1, in accordance with the Raman spectrum of polyetherimide. Conclusions Numerous plastic particles are generated during microkeratome oscillation and are deposited at the interface during LASIK. The particles persist unaltered for at least 1 year.

Wiping microkeratome blades with sterile 100% alcohol to prevent diffuse lamellar keratitis after laser in situ keratomileusis

Purpose To report our experience in preventing diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) by wiping the microkeratome blade with sterile 100% alcohol. Setting Enaim Refractive Surgery Center, Jerusalem, Israel. Methods Laser in situ keratomileusis was performed in 24 patients (48 eyes) on the same day by the same surgeon. The environment and instruments were identical in all cases. A new blade was used in both eyes of each patient. All blades were from the same batch and were randomly assigned to 2 groups. In the alcohol group, 12 blades were wiped with a Merocel® surgical spear (Medtronic Solan) dipped in 100% alcohol and rinsed with balanced salt solution (BSS®) before they were mounted in a Hansatome® microkeratome (Bausch & Lomb Co.); in the control group, 12 blades were wiped with a Merocel surgical spear dipped in BSS and rinsed with BSS. All patients were examined on the first postoperative day. Results Grade I to II DLK was diagnosed in 7 eyes of 4 patients in the control group (29%). No DLK was diagnosed in the alcohol group. Conclusion Wiping the microkeratome blade with 100% alcohol before mounting may remove a substance from the manufacturing or sterilization process that can cause DLK.