Crescent Blade Research Articles

“En bloc” combined 270-degree keratolimbal allograft with central lamellar keratoplasty for severe limbal stem cell deficiency secondary to mustard gas exposure

BackgroundSevere limbal stem cell deficiency (LSCD) resulting from chronic and delayed-onset mustard gas keratopathy (MGK) presents substantial management challenges. This article introduces an “en bloc” surgical procedure combining a 270-degree keratolimbal allograft (KLAL) with central lamellar keratoplasty (CLK) as a novel approach to treat this condition. MethodsA retrospective case series was conducted at Labbafinejad Medical Center in Tehran, Iran, from 2002 to 2019, including 13 eyes from 13 male patients diagnosed with chronic and delayed-onset MGK. Each patient underwent the combined 270-degree KLAL and central LK procedure. A 270-degree peritomy, sparing the superior quadrant, was performed. A lamellar dissection using a crescent blade and a blunt Melles dissector was carried out, extending 2 mm from the limbus. Fresh donor tissue with intact 270-degree limbo-conjunctiva, obtained from a whole globe, was prepared to match the recipient bed and sutured into place. Postoperative outcomes and success including ocular surface integrity, graft longevity, and best-corrected visual acuity (BCVA), were evaluated. ResultsThe average follow-up period was 87.6 ± 49.8 months. Surgical success was achieved in 12 of 13 patients (92.3 %). Preoperative BCVA improved from 1.07 ± 0.24 (approximately 20/250) logMAR to 0.63 ± 0.30 (approximately 20/80) logMAR postoperatively. One patient experienced immune rejection of the KLAL graft, while two patients had episodes of corneal rejection, all successfully managed with aggressive immunosuppressive therapy. ConclusionsThe “en bloc KLAL + CLK” procedure demonstrates promising long-term outcomes in managing chronic and delayed-onset MGK associated with severe LSCD. This approach offers advantages, including reduced surgical complexity, minimized antigenic load, and better anatomical alignment, leading to successful ocular surface restoration and improved visual acuity.

The ophthalmologic crescent blade in endonasal surgery.

The angled tip and small size of the crescent blade provide versatility for its use in a variety of endonasal procedures. The crescent blade enables cutting along 180° from the tip, ensuring a tangential cut through the mucosa, which is important for flap viability. The disposable nature of the blade ensures that it is always sharp, allowing for its use in mucosal and cartilaginous cuts.

Retrospective Analysis of a New Intrastromal Dissection Technique Using the Retinal Reflex for Deep Anterior Lamellar Keratoplasty.

The purpose of this study was to describe a new surgical technique for deep anterior lamellar keratoplasty. All pupils in the recipient eyes were dilated preoperatively. Vertical grooving was performed using a crescent blade with a width of 5 mm and a depth of one-third to half corneal thickness on the temporal side of the limbus. Stromal dissection was performed as close as possible to Descemet membrane by observing the gap between the gold line by retinal reflex and the front edge of the crescent blade. Lamellar dissection was performed along the lamellar plane using corneal dissectors. The ophthalmic viscoelastic device was injected into the intrastromal pocket to separate the anterior and posterior stroma and an anterior corneal lamella was excised. A donor cornea was sutured into the recipient bed. In 18 eyes, none of the patients had Descemet membrane rupture during surgery. The mean postoperative residual stromal thickness was 80 ± 31 μm. The mean central corneal thickness after surgery was 660 ± 69 μm. At the last follow-up, the cornea was cleared in all 18 eyes on slit-lamp examination. We estimated the residual stromal thickness based on the gap between the gold line by the retinal reflex and crescent blade, and intrastromal lamellar dissection was performed using a smooth corneal dissector. Consequently, the surface of stromal dissection was smooth, and the residual stromal thickness was even.

The Impact of Standard Cross-Linking on the Corneal Optical Density-Age Relationship in Keratoconus After Mechanical Stripping of the Epithelium.

Background: To determine if cross-linking (CXL) treatment modifies any pre-existing association between corneal optical density (COD) and age in keratoconus free of corneal scarring. Methods: COD was monitored in two groups (i) before and after standard CXL treatment for keratoconus (de-epithelization with a crescent blade, n = 69 eyes) and (ii) age/gender-matched cases without any signs of keratoconus (n = 24 eyes). Seven different markers of COD were quantified using a 0-100 grey scale, supplied with Pentacam™ software. Results: Mean age (±sd, range) in Group I (19 females and 50 males) was 24.2 years (±7.2, 11-44) and in Group II (9 females and 15 males), it was 24.7 years (±7.6, 17-45). COD over the apex and along the depth of the cornea (y, arbitrary scale units) was associated with age (x, in years) in Group I at preop (y = 0.08x + 13.12, r s = 0.350 and p=0.003), at 12 months postop (y = 0.08x + 15.15, r s = 0.295 and p=0.014) and in Group II, at the start (y = 0.16x + 11.28, r s = 0.474 and p=0.019) and 12 months later (y = 0.24x + 8.63, r s = 0.600 and p=0.002). The change in COD following CXL was significantly associated with the preop value. Conclusion: CXL initially breaks down the pre-existing relationship between COD and age. This is re-established by 12 months postop. The CXL induced change in COD depends on the preop value but not on the patient's age.

Novel tunnel staining technique to reduce premature entry in manual small-incision cataract surgery.

Mastering manual small-incision cataract surgery (MSICS) for beginner surgeons is difficult. In the initial days of residency or training, surgeons struggle to make a proper scleral tunnel and keratome entry. It commonly results in premature entry and iris prolapse. Most of the literature has shed light on premature entry during tunnel construction by a crescent blade, whereas a significant majority of iris prolapse happens due to improper keratome entry. This novel trypan blue dye-assisted tunnel staining (TBTS) technique helps in proper tunnel demarcation which can reduce the incidence of premature entry with a keratome.

Refractive Corneal Lenticule Extraction With the CLEAR Femtosecond Laser Application.

The aim of this study was to evaluate a new femtosecond laser application for refractive corneal lenticule extraction with suction control and computerized regulation of centration and alignment (Ziemer CLEAR). This was a retrospective, consecutive, noncomparative case series study. Patients undergoing CLEAR for spherical equivalent (SE) between -3 and -10 D, evaluating SE, defocus equivalent, refractive astigmatism, visual acuity, and centration at 10 months were evaluated in the study. Fifty-three eyes of 42 patients (mean age 40.4 ± 8.6 years) were included, with preoperative SE -5.99 ± 1.49 D and mean corrected distance visual acuity (CDVA) of 0.05 ± 0.07 logMAR. With no suction losses, an intact lenticule was extracted in all eyes. In 6 eyes, peripheral adhesion was resolved by lenticulerrhexis, and in 1 eye, the incision was opened by a crescent blade. Moderate interface inflammation occurred in 3 eyes. At day 1, in the 42 eyes with uneventful surgery, the mean CDVA was 20/27, whereas in the 11 eyes with extra surgical manipulations, it was 20/36 ( P = 0.04). At 10 months, for the 53 eyes, the mean uncorrected distance visual acuity was 0.05 ± 0.09 logMAR; in 37 eyes (70%), it was 20/25 or better; and the mean CDVA was 0.04 ± 0.06 logMAR. Eight eyes (15%) lost 1 logMAR line. The mean SE was -0.13 ± 0.15 D. The mean defocus equivalent was 0.33 ± 0.32 D, with 46 eyes (87%) ≤0.50 D and 52 eyes (98%) ≤1 D. Refractive astigmatism was ≤0.50 D in 48 eyes (90%). The efficacy index was 1.00, and the safety index was 0.98. The mean decentration from the corneal vertex was 0.28 ± 0.07 mm. The application yielded good predictability, efficacy, and safety. Slower visual recovery was observed after extra surgical manipulations.

Author's reply to comments on “comparison of the scleral tunnel constructed with crescent versus razor blade using the anterior segment optical coherence tomography”

Author's reply to comments on “comparison of the scleral tunnel constructed with crescent versus razor blade using the anterior segment optical coherence tomography”

The Role of Using Motorized Diamond Burr Polisher Instrument in Minimizing the Recurrent Rate of Pterygium Excision

To compare the effects of using motorized diamond burr polisher in pterygium excision versus manual polishing of the corneoscleral bed in reducing the recurrent rate. A prospective, comparative and interventional study of 90 consecutive patients with different grads of primary pterygium, who underwent pterygium excision at Shahid Aso teaching eye hospital in Sulaimani city, between August 2018 till September 2019, which was performed by single surgeon. In group A (45) eyes polishing of the corneoscleral bed done using motorized diamond polishing burr, and in group B (45) eyes using manual crescent blade for polishing. Recurrent rate was evaluated after about (8±2) months postoperatively. Ethical consideration of the risks and the benefits of the procedure was observed for each individual patient. A 90 patients with the mean age of group A (48.84±12.7) years and group B (49.67±12.3) years, complained of different grads of primary pterygium, group A had 31(68.9%) male and 14(31.1%) female, while group B had 22(48.9%) male and 23(51.1%) female. Each individual factors like age, gender, visual acuity, BCVA pre and postoperatively, IOP measurement, dryness of the eye and risk factors like smoking and UV exposure affecting the recurrence were assessed. In both groups the main indication for surgery was sign of irritation. The mean surgical time was calculated and the difference between two groups were significant. After follow-up of average six months the outcomes and recurrent rate were checked, recurrent rate was in group A 1(2.2%) while in group B was 6(13.3%) patients. it significantly decreased. Corneal scar happens in only 1(2.2%) case of group A while in 11(24.4%) cases in group B, Corneal scar was statistically significant. In both groups the change of BCVA was significant but the visual change was more significant in group A in compare to group B. Motorized diamond burr is a safe instrument for polishing the cornea during pterygium excision, it is easy to handle, low price, need lesser operative time, its effect on recurrence postoperatively is significant and beside it leaves lesser corneal scar and early visual recovery postoperatively.

Comparison of the scleral tunnel constructed with crescent versus razor blade using the anterior segment optical coherence tomography

Aim: The aim of this study is to compare and contrast the efficacy of a razor blade against crescent, in constructing a scleral tunnel in temporal small-incision cataract surgery (SICS) in a community setup. The following parameters were considered for the comparative analysis: a) Structural anatomical dimensions using the anterior segment optical coherence tomography (ASOCT), b)Tunnel integrity based on the need for suturing or subsequent resuturing and c) Section outcome in terms of any associated tunnel complications. Methods: A prospective, comparative study of 100 consecutive cases of temporal SICS was done. The cases were randomly divided to undergo the surgery with tunnel construction either with a crescent knife or a razor blade (50 eyes each), by a singleoperating surgeon (Dr SR). The structural dimensions and integrity of the tunnel were noted using an AS-OCT on the 1st postoperative day. Tunnel-related complications were noted both intra and postoperatively. Results: Of the 100 eyes operated, the mean average depth at section, with crescent was found to be 526 μ, while that with blade was 598 μ. The mean average depth at internal entry was found to be 607 μ with crescent and that with blade was 670 μ. Self-sealing wound was achieved in 49 of the 50 cases with crescent as well as with blade, with only 1 tunnel requiring 1 suture for anterior chamber (AC) formation in case of both crescent and blade. Tunnel complications included Descemet's membrane detachment in 1 eye and premature entry in 1 eye, in razor blade constructed tunnel. The time taken with crescent was on a mean average 32.9 s, while that with blade was 27.3 s. Conclusion: Razor blade constructed scleral tunnels are slightly deeper compared to crescent as noted on AS-OCT. Integrity and complication rates being comparable between the two. The razor blade could be considered as a safe, equally efficacious, if not better, and an economical alternate to crescent knife in a high-volume community setup.

Sutureless intrascleral fixation of intraocular lens through self-sealing sclerotomy wounds using haptic externalization and reinternalization technique

In eyes with absent or insufficient capsule support, three-piece posterior chamber intraocular lens (PC IOL) may be fixed to the sclera. Previous techniques involve the use of sutures, flaps, glue, needles, trocars, or intrascleral tunnels to fixate the distal tips of the haptics intrasclerally. Herein we describe a modified technique for the sutureless scleral fixation of a standard 3-piece PC IOL using self-sealing sclerotomies created with a crescent blade and a 20-gauge microvitreoretinal blade, and then reinserting the haptics to leave the tips inside the vitreous cavity. We believe the relative simplicity of this technique makes it widely applicable for the placement of an IOL with insufficient capsule support.

Primary Modified Predescemetic Deep Anterior Lamellar Keratoplasty in Acute Corneal Hydrops

To report primary treatment of acute corneal hydrops (CH) with a modified technique of predescemetic deep anterior lamellar keratoplasty (pdDALK). This prospective interventional case series included 9 eyes with acute CH that underwent pdDALK as primary treatment. Technique modifications included a bevel-up needle, creating tissue emphysema as a guide for dissection, using small aliquots of air directed away from break, manual deeper dissection using a blunt dissector, centripetal dissection leaving the area of Descemet membrane (DM) break for last, retention of minimal stroma above DM tear, and tamponade of DM tear with air in the anterior chamber. In eyes with extensive area of edema or thin residual stroma, an inked trephine mark was manually deepened with a sharp crescent blade, followed by other modifications. All patients underwent uneventful surgery without enlargement of DM tear. The average follow-up period was 18 ± 13 months. All showed a clear, nonedematous graft with an area of DM defect seen and overlying cornea continuing to remain clear at final postoperative follow-up. ASOCT showed 90.8 ± 32 μm residual predescemetic host stroma on either side of the defect. CDVA improved from 0.002 ± 0.005 preoperatively to 0.35 ± 0.1 by an average of 2.3 ± 0.8 weeks and to 0.52 ± 0.13 at final postoperative follow-up. Primary pdDALK was possible as single-stage definitive treatment with early visual rehabilitation and avoidance of scarring in our case series. Simultaneous correction of pathology by closure of DM break, anatomical correction of ectasia and thinning, optical correction by improved corneal topography and by regaining corneal structure and transparency, and retention of host DM and endothelium are advantages. Advanced DALK surgeons may use this technique.

Simple Preoperative Ink Test as a Novel Adjunct to Intrastromal Keratopigmentation for Post-laser Peripheral Iridotomy Dysphotopsias.

To describe a simple preoperative ink test as a novel adjunct to intrastromal keratopigmentation for post-laser peripheral iridotomy (LPI) dysphotopsias. A surgical marking pen is applied to the area over a peripheral iridotomy before intrastromal keratopigmentation. The patient can then assess whether there is any improvement in their symptoms of dysphotopsias. Manual intrastromal keratopigmentation can then be performed using a crescent blade into the clear cornea at 50% depth and tunneled centrally to create a pocket ensuring that the peripheral iridotomy is fully occluded. The crescent blade is coated with an alcohol-based commercially available black tattoo pigment, and the pocket is filled. We have used the preoperative ink marker test on 5 eyes in patients with post-LPI (4 temporal and 1 superior) dysphotopsias before performing intrastromal keratopigmentation, with good patient satisfaction. Patients report immediate symptomatic relief after the procedure. This ink marking technique can also be extended to help identify which iris defect is symptomatic in patients with multiple iris defects. The preoperative ink test before intrastromal keratopigmentation is a novel adjunct to the treatment of post-LPI dysphotopsias.

Novel Technique for Descemet Membrane Remnant Stripping in Hazy Cornea During DSAEK.

To describe a novel technique for removal of Descemet membrane (DM) tags or remnants in hazy corneas during Descemet stripping automated endothelial keratoplasty. The DM tags or remnants may be difficult to visualize in the presence of hazy corneas. To identify and remove the residual DM remnants and tags, a crescent knife is introduced into the anterior chamber through the 3.2 mm temporal corneoscleral tunnel and is placed intracamerally, parallel to the iris plane underneath scored DM (which had been previously stained with the trypan blue solution). Under direct illumination from the operating microscope, the crescent blade acts as a light reflector so that the blue DM remnants and tags are highlighted against the silver background of the crescent knife. These tags or remnants may then be identified and then peeled off using intravitreal forceps. The donor lenticule is inserted and air tamponade is used for apposition of the donor lenticule to the recipient host. This technique was used successfully in 10 eyes. No DM tags were present in any of the eyes postoperatively and all the grafts were well apposed. The crescent blade as a reflector is a simple and useful tool to identify trypan blue stained DM remnants or tags in the presence of hazy corneas during endothelial keratoplasty.

Blunt scissors stromal dissection technique for deep anterior lamellar keratoplasty

ObjectiveWe describe a modified technique for performing lamellar dissection in deep anterior lamellar keratoplasty after failure to achieve a “big bubble” detachment of Descemet’s membrane (DM) with deep intrastromal pneumatic injection.MethodsThe technique utilizes blunt lamellar dissection with blunt-tipped corneal mini scissors as an alternative to a crescent blade, which can be difficult for surgeons to master and is associated with a high risk of perforation.ResultsOther techniques of blunt dissection, such as the Melles technique, cannot be utilized after failure to achieve a big bubble, as emphysema in the stroma prevents visualization of the spatula. In contrast, our blunt scissors lamellar dissection technique takes advantage of the emphysema and microdetachments of DM created by the pneumatic injection.ConclusionThis technique provides deep anterior lamellar keratoplasty surgeons with a simple, alternative method of baring DM or achieving a pre-DM plane with minimal residual stroma, after failure to achieve a big bubble.

Sutureless Intrascleral Pocket Technique of Transscleral Fixation of Intraocular Lens in Previous Vitrectomized Eyes

In this case series, we assessed a new technique, the intrascleral pocket procedure of transscleral fixation (TF) of the intraocular lens (IOL) in post-vitrectomized eyes. We performed the transscleral fixation of IOL in four aphakic patients who underwent pars plana vitrectomy. Two points 180° apart were marked at the limbus. A 2-mm-sized intrascleral pocket was created by lamellar dissection using a crescent blade without conjunctival dissection. A 2.8-mm clear corneal incision (CCI) was made using a keratome. Prolene sutures were exteriorized through the CCI pocket and a three-piece foldable acrylic IOL was injected via CCI and the ends of the haptics were exteriorized through the CCI. The prolene sutures for each haptic in the intrascleral pocket bed were then tied and knots were buried under scleral flaps. No patient had complaints such as conjunctival irritation, and visual acuity was almost identical to preoperative best-corrected visual acuity at day 1 postoperatively. IOLs were well placed without tilting or subluxation. They had no wound dehiscence or endophthalmitis postoperatively. The intrascleral pocket procedure of TF without the need for conjunctival dissection is a successful method for sulcus fixation in post-vitrectomized eyes predisposed to developing glaucoma.

Manual cataract extraction via a subconjunctival limbus oblique incision for mature cataracts.

Aims:To report the technique and outcomes of sutureless manual cataract extraction via a subconjunctival limbus oblique incision for mature cataracts.Materials and Methods:This retrospective study comprised of 112 eyes of 83 patients with mature cataract who all had manual cataract extraction via a subconjunctival limbus oblique incision. A transconjunctival tunnel is fashioned with a 3.0 mm keratome, 0.5 mm behind the limbal vascular arcades. A limbal tunnel, with a transverse extent of 9 mm in the cornea and 7.0 mm in the limbus, is created beneath the conjunctival/Tenon's tissue using an angled bevel-up crescent blade. Outcome measures included visual acuity, intraoperative complications, surgically induced astigmatism, endothelial cell loss rate and surgery time.Results:Self-sealing wound was achieved in 112 eyes (98.2%). The nucleus was delivered in whole in 108 eyes (96.4%). Intraoperative complications included hyphema in 3 eyes (2.7%), iridodialysis in 2 eyes 1.8%), posterior capsular rupture and zonular dialysis in 2 eyes (1.8%). At the 3-month follow-up, 91% patients achieved a best-corrected visual acuity of 20/20 or better, the mean of surgically induced astigmatism was -0.62 ± 0.41 Diopters and endothelial cell loss was 4.2%. Average surgical time was 3.75 min per case.Conclusion:This subconjunctival limbus oblique incision has the potential to serve as safe and effective technique for mature cataracts.

Stromal Lamellar Dissection of the Donor Disc

To describe a surgical technique to decrease the incidence and potential complications of an eccentric trephination and improve graft adherence during Descemet stripping automated endothelial keratoplasty. Technique description. After resection of the anterior lamella with the microkeratome, the corneoscleral rim in the artificial anterior chamber (AC) is brought under view of the operating microscope and the deep dissection plane of the microkeratome is extended 360 degrees as far peripherally as permitted by the Moria artificial anterior chamber using a crescent blade and 0.12-mm Colibri forceps. The central stroma is marked with gentian violet, and the donor button is released from the AC and then carefully placed and centered on the punching block endothelial side up using the gentian violet mark as a guide and trephined to the desired diameter. The donor graft may then be inserted by the surgeon's preferred technique. This simple technique allows the surgeon to consistently increase the lamellar dissection diameter while reducing the peripheral graft thickness, which becomes particularly important when the trephination is eccentric. This technique may lead to improved donor adherence and a decrease in the incidence of donor lenticule configuration -related complications.

Waiting Is the Hardest Part

Waiting Is the Hardest Part

Tectonic Deep Anterior Lamellar Keratoplasty in Impending Corneal Perforation Using Cryopreserved Cornea

We report a case of tectonic corneal transplantation for impending corneal perforation to preserve anatomic integrity using cryopreserved donor tissue. An 82-year-old woman exhibiting impending corneal perforation suffered from moderate ocular pain in the left eye for one week. After abnormal tissues around the impending perforation area were carefully peeled away using a Crescent blade and Vannas scissors, the patient received tectonic deep anterior lamellar keratoplasty using a cryopreserved cornea stored in Optisol GS® solution at -70℃ for four weeks. At six months after surgery, the cornea remained transparent and restored the normal corneal thickness. There were no complications such as corneal haze or scars, graft rejection, recurrent corneal ulcer, and postoperative rise of intraocular pressure. Cryopreserved donor lamellar tissue is an effective substitute in emergency tectonic lamellar keratoplasty, such as impending corneal perforation and severe necrotic corneal keratitis.

Comparison of Techniques Used for Removing the Recipient Stroma in Anterior Lamellar Keratoplasty

To compare 3 techniques used for removing the recipient stroma during anterior lamellar keratoplasty (ALK): the "big-bubble" technique, manual dissection using a crescent blade and slitlamp operating microscope, and microkeratome lamellar cut. Retrospective comparative cohort study of 69 consecutive ALKs and 69 consecutive penetrating keratoplasties (PKs). Manifest refraction, slitlamp examination, Goldmann tonometry, ultrasound pachymetry, specular microscopy, and confocal microscopy findings were recorded. The 12-month graft survival estimate was 98.5% in the ALK group and 94.1% in the PK group (P = .19). Higher endothelial cell density was found after ALK (P < .001). At 12 months (before suture removal), 53% of eyes that underwent ALK and 44% of eyes that underwent PK had 20/40 or better spectacle-corrected visual acuity (P = .24). In keratoconic eyes, these values were 83% and 69%, respectively (P = .18). Significant differences in visual acuity, corneal central thickness, and keratocyte density among ALK subgroups were found, with the best results obtained using the big-bubble technique and the worst results obtained using the microkeratome. In eyes that underwent ALK, visual acuity increased with keratocyte density. Better results were obtained after ALK vs PK, and the big-bubble technique seemed to provide the best results.