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Biomolecules Apr 2023Bowman's layer is an acellular layer in the anterior stroma found in the corneas of humans, most other primates, chickens, and some other species. Many other species,... (Review)
Review
Bowman's layer is an acellular layer in the anterior stroma found in the corneas of humans, most other primates, chickens, and some other species. Many other species, however, including the rabbit, dog, wolf, cat, tiger, and lion, do not have a Bowman's layer. Millions of humans who have had photorefractive keratectomy over the past thirty plus years have had Bowman's layer removed by excimer laser ablation over their central cornea without apparent sequelae. A prior study showed that Bowman's layer does not contribute significantly to mechanical stability within the cornea. Bowman's layer does not have a barrier function, as many cytokines and growth factors, as well as other molecules, such as EBM component perlecan, pass bidirectionally through Bowman's layer in normal corneal functions, and during the response to epithelial scrape injury. We hypothesized that Bowman's layer represents a visible indicator of ongoing cytokine and growth factor-mediated interactions that occur between corneal epithelial cells (and corneal endothelial cells) and stromal keratocytes that maintain the normal corneal tissue organization via negative chemotactic and apoptotic effects of modulators produced by the epithelium on stromal keratocytes. Interleukin-1 alpha, produced constitutively by corneal epithelial cells and endothelial cells, is thought to be one of these cytokines. Bowman's layer is destroyed in corneas with advanced Fuchs' dystrophy or pseudophakic bullous keratopathy when the epithelium becomes edematous and dysfunctional, and fibrovascular tissue commonly develops beneath and/or within the epithelium in these corneas. Bowman's-like layers have been noted to develop surrounding epithelial plugs within the stromal incisions years after radial keratotomy. Although there are species-related differences in corneal wound healing, and even between strains within a species, these differences are not related to the presence or absence of Bowman's layer.
Topics: Humans; Animals; Dogs; Rabbits; Epithelium, Corneal; Endothelial Cells; Corneal Stroma; Chickens; Cornea; Wound Healing; Cytokines
PubMed: 37238641
DOI: 10.3390/biom13050771 -
Cell Journal Apr 2023Recent studies imply extensive applications for the human amniotic membrane (hAM) and its extract in medicine and ophthalmology. The content of hAM meets many...
The Effect of Amniotic Membrane Extracted Eye Drop on Repairing The Corneal Epithelial in Patients after Trans-Epithelial Photorefractive Keratectomy: An Interventional and Historical Study.
OBJECTIVE
Recent studies imply extensive applications for the human amniotic membrane (hAM) and its extract in medicine and ophthalmology. The content of hAM meets many requirements in eye surgeries, such as refractive surgery as the most important and commonly used method for treating the dramatically increasing refractive errors. However, they are associated with complications such as corneal haziness and corneal ulcer. This study was designed to evaluate the impact of amniotic membrane extracted eye drop (AMEED) on Trans-PRK surgery complications.
MATERIALS AND METHODS
This randomized controlled trial was performed during two years (July 1, 2019-September 1, 2020). Thirty-two patients (64 eyes), including 17 females and 15 males, aged 20 to 50 years (mean age of 29.59 ± 6.51) with spherical equivalent between -5 to -1.5 underwent Trans Epithelial Photorefractive Keratectomy (Trans-PRK) surgery. One eye was selected per case (case group) and the other eye was considered as control. Randomization was done using the random allocation rule. The case group was treated with AMEED, and the artificial tear drop every 4 hours. The control eyes received artificial tear drops instilled every 4 hours. The evaluation continued for three days after the Trans-PRK surgery.
RESULTS
A significant decrease in CED size was found in the AMEED group on the second day after surgery (P=0.046). Also, this group had a substantial reduction in pain, hyperemia, and haziness.
CONCLUSION
This study showed that AMEED drop can increase the healing rate of corneal epithelial lesions after Trans- PRK surgery and reduce the early and late complications of Trans-PRK surgery. Researchers and Ophthalmologists should consider AMEED as a selection in patients with persistent corneal epithelial defects and patients who have difficulty in corneal epithelial healing. We understood AMEED has a different effect on the cornea after surgery; therefore, the researcher must know AMEED's exact ingredients and help expand AMEED uses (registration number: TCTR20230306001).
PubMed: 37210641
DOI: 10.22074/cellj.2022.8165 -
International Journal of Ophthalmology 2023
PubMed: 37206164
DOI: 10.18240/ijo.2023.05.23 -
Indian Journal of Ophthalmology May 2023To compare post-operative pain perception using bandage contact lens (BCL) stored at 2-8°C (Cold BCL, CL-BCL) or room temperature (23 - 25°C, RT-BCL) after...
PURPOSE
To compare post-operative pain perception using bandage contact lens (BCL) stored at 2-8°C (Cold BCL, CL-BCL) or room temperature (23 - 25°C, RT-BCL) after photorefractive keratectomy (PRK) or corneal collagen-crosslinking (CXL) and determine status of nociception associated factors.
METHODS
In this prospective interventional study, 56 patients undergoing PRK for refractive correction and 100 keratoconus (KC) undergoing CXL were recruited following approval from the institutional ethics committee with informed consent. Patients undergoing bilateral PRK received RT-BCL on one eye and CL-BCL on the other. Pain was graded by Wong-Baker scoring on the first post-operative day (PoD1). Expression of transient receptor potential channels (TRPV1, TRPA1, TRPM8), calcitonin gene-related peptide (CGRP) and IL-6 was measured in cellular content from used BCLs collected on PoD1. Equal number of KC patients received RT-BCL or CL-BCL post-CXL. Pain was graded by Wong-Baker scoring on PoD1.
RESULTS
Pain scores on PoD1 were significantly (P < 0.0001) reduced in subjects receiving CL-BCL (Mean ± SD: 2.6 ± 2.1) compared to RT-BCL (6.0 ± 2.4) post-PRK. 80.4% of subjects reported reduced pain scores with CL-BCL. 19.6% reported no change or increased pain scores with CL-BCL. TRPM8 expression was significantly (P < 0.05) increased in BCL of subjects reporting reduced pain with CL-BCL compared to those who did not. Pain scores on PoD1 were significantly (P < 0.0001) reduced in subjects receiving CL-BCL (3.2 ± 2.1) compared to RT-BCL (7.2 ± 1.8) post-CXL.
CONCLUSION
The simple approach of using a cold BCL post-operatively substantially reduced pain perception and could overcome post-operative pain-related limited acceptance of PRK/CXL.
Topics: Humans; Photorefractive Keratectomy; Visual Acuity; Prospective Studies; Keratoconus; Bandages; Contact Lenses; Pain, Postoperative; Pain Perception; Collagen; Cross-Linking Reagents; Photosensitizing Agents
PubMed: 37203044
DOI: 10.4103/IJO.IJO_2757_22 -
Indian Journal of Ophthalmology May 2023To compare visual outcomes of early enhancement following small incision lenticule extraction (SMILE) versus laser in situ keratomileusis (LASIK).
PURPOSE
To compare visual outcomes of early enhancement following small incision lenticule extraction (SMILE) versus laser in situ keratomileusis (LASIK).
METHODS
Retrospective analysis of eyes (patients operated in the setting of a tertiary eye care hospital between 2014 and 2020) requiring early enhancement (within one year of primary surgery) was conducted. Stability of refractive error, corneal tomography, and anterior segment Optical Coherence Tomography (AS-OCT) for epithelial thickness was performed. The correction post regression was done using photorefractive keratectomy and flap lift in eyes, wherein the primary procedure was SMILE and LASIK, respectively. Pre- and post enhancement corrected and uncorrected distance visual acuity (CDVA and UDVA), mean refractive spherical equivalent (MRSE), and cylinder were analyzed. IBM SPSS statistical software.
RESULTS
In total, 6350 and 8176 eyes post SMILE and LASIK, respectively, were analyzed. Of these, 32 eyes of 26 patients (0.5%) post SMILE and 36 eyes of 32 patients (0.44%) post-LASIK required enhancement. Post enhancement (flap lift in LASIK, and PRK in SMILE group) UDVA was logMAR 0.02 ± 0.05 and 0.09 ± 0.16 (P = 0.009), respectively. There was no significant difference between the refractive sphere (P = 0.33) and MRSE (P = 0.09). In total, 62.5% of the eyes in the SMILE group and 80.5% in the LASIK group had a UDVA of 20/20 or better (P = 0.04).
CONCLUSION
PRK post SMILE demonstrated comparable results to flap lift post LASIK and is a safe and effective approach for early enhancement post SMILE.
Topics: Humans; Keratomileusis, Laser In Situ; Retrospective Studies; Corneal Stroma; Treatment Outcome; Follow-Up Studies; Lasers, Excimer; Myopia; Refraction, Ocular; Corneal Wavefront Aberration; Surgical Wound
PubMed: 37203042
DOI: 10.4103/IJO.IJO_3209_22 -
BMC Ophthalmology May 2023In eyes with hyperopia, astigmatism, and mixed astigmatism Transepithelial photorefractive keratectomy (TransPRK) is a modality of surface ablation surgery. We center on...
BACKGROUND
In eyes with hyperopia, astigmatism, and mixed astigmatism Transepithelial photorefractive keratectomy (TransPRK) is a modality of surface ablation surgery. We center on the corneal vertex for all our treatments (all have an offset to the center of the pupil) and wanted to compare the visual results of symmetrical profile treatments versus asymmetrical profile treatments (the center of the treatment on the vertex and the boundaries with the pupil center) using TransPRK as corneal refractive surgery.
METHODS
We retrospectively analyzed two consecutive groups of eyes treated with TransPRK in the Aurelios Augenlaserzentrum Recklinghausen: 47 eyes treated with symmetrical offset and 51 eyes treated with asymmetrical offset. The intergroup comparisons were assessed using unpaired Student's T-tests, whereas preoperative to postoperative changes were assessed using paired Student's T-tests.
RESULTS
Refractive outcomes were good for both groups. 83 and 88% of eyes were within the spherical equivalent of 0.5 D from the target in the symmetric and asymmetric offset groups, respectively. 85 and 84% of eyes had a postoperative astigmatism of 0.5 D or lower in the symmetric and asymmetric offset groups, respectively.
CONCLUSION
We have not found a significant difference in the refractive outcomes between the symmetric group and the asymmetric group of eyes treated both with TransPRK for preoperatively hyperopic or mixed astigmatism.
Topics: Humans; Astigmatism; Visual Acuity; Lasers, Excimer; Retrospective Studies; Refraction, Ocular; Photorefractive Keratectomy; Hyperopia; Treatment Outcome
PubMed: 37198622
DOI: 10.1186/s12886-023-02971-9 -
International Medical Case Reports... 2023To report morphologic and functional changes after topography-guided trans-epithelial photorefractive keratectomy (PRK) combined with phototherapeutic keratectomy (PTK)...
PURPOSE
To report morphologic and functional changes after topography-guided trans-epithelial photorefractive keratectomy (PRK) combined with phototherapeutic keratectomy (PTK) for recalcitrant recurrent corneal erosions in Lattice Corneal Dystrophy (LCD).
METHODS
One case report.
RESULTS
A 78-year-old man presented us with decreased visual acuity [20/100 in right eye (RE), and 20/400 in left eye (LE)], and redness with foreign body sensation in both eyes. Clinical examination revealed epithelial erosions, and linear stromal opacities involving the center of the cornea in both eyes, supporting the diagnosis of LCD. Several medical approaches including autologous serum, amniotic membrane extract, and nerve growth factor eye drops allowed a temporary improvement in symptoms. A single-step topography-guided trans-epithelial PRK combined with PTK (CIPTA2 software, iVis Technologies) was performed in both eyes. After surface ablation using PRK, PTK was performed using masking agents (1% hydroxy-methylcellulose) to smooth the ablated surface. Subsequently, 0.02% Mitomycin C was applied over the ablated surface. At the 3-month follow-up, a resolution of corneal erosions, and stromal opacities were observed in both eyes, with a visual improvement to 20/25 in the RE and 20/50 in the LE. Furthermore, spherical equivalent, keratometric astigmatism, and corneal morphological irregularity index improved.
CONCLUSION
Recalcitrant corneal erosions and stromal opacities in LCD may be successfully treated using combined topography-guided trans-epithelial PRK and PTK.
PubMed: 37193056
DOI: 10.2147/IMCRJ.S403451 -
Translational Vision Science &... May 2023To evaluate wound healing in rabbit corneas that developed a spontaneous persistent epithelial defect (PED) after photorefractive keratectomy (PRK).
PURPOSE
To evaluate wound healing in rabbit corneas that developed a spontaneous persistent epithelial defect (PED) after photorefractive keratectomy (PRK).
METHODS
Forty-eight 10- to 15-week-old female New Zealand White rabbits weighing 2.5 to 3.0 kg underwent either -3 diopter (D) or -9 D PRK to generate a series of corneas to study wound healing after injury. During that series, seven corneas developed a PED detected with 1% fluorescein staining at a slit lamp that either did not have epithelial closure by 1 week after surgery or subsequently had the closed epithelium break down to form a PED 2 to 3 weeks after surgery. The corneas had slit-lamp photography, with and without 1% fluorescein, and were removed from the normal PRK series. Each PED cornea was evaluated using immunohistochemistry for the myofibroblast marker α-smooth muscle actin (α-SMA), keratocyte marker keratocan, and mesenchymal cell marker vimentin, as well as basement membrane components perlecan and collagen type IV.
RESULTS
All seven corneas that had PRK with a PED, even the two evaluated at only 1 week after PRK, had α-SMA-positive myofibroblasts populating the anterior stroma within the PED, along with comingled α-SMA-negative cells that were likely corneal fibroblasts and possibly bone marrow-derived fibrocytes. Both perlecan and collagen type IV accumulated in the anterior stroma of the epithelial defects without an epithelial basement membrane, likely produced by corneal fibroblasts to modulate transforming growth factor-β entering the stroma from the tears and peripheral epithelium.
CONCLUSIONS
Corneas with a PED that occurred following PRK (a procedure that produces a transient neurotropic state in the cornea) had myofibroblasts populating the superficial stroma within the epithelial defect as early as 1 week after the surgery.
TRANSLATIONAL RELEVANCE
Pharmacologic treatments that trigger myofibroblast apoptosis, including topical losartan, could facilitate decreased scarring fibrosis in corneas with a PED.
Topics: Rabbits; Female; Animals; Photorefractive Keratectomy; Epithelium, Corneal; Collagen Type IV; Cornea; Fluoresceins
PubMed: 37184499
DOI: 10.1167/tvst.12.5.15 -
Cureus Mar 2023Purpose To compare the visual outcome of transepithelial photorefractive keratectomy (PRK) against alcohol-assisted PRK in treating low-to-moderate myopia with or...
Purpose To compare the visual outcome of transepithelial photorefractive keratectomy (PRK) against alcohol-assisted PRK in treating low-to-moderate myopia with or without astigmatism. Setting Dhahran Eye Specialist Hospital, Dhahran, Saudi Arabia. Design This is a retrospective study. Methods Forty eyes of 22 patients with myopia from -0.75 to -6.00 diopters (D) with or without astigmatism from 0 to -3D were included in this study. Preoperative and postoperative data of 20 eyes from 11 patients who underwent transepithelial PRK were compared with 20 eyes from 11 patients who underwent alcohol-assisted PRK were collected and analyzed. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest spherical equivalence (SE), manifest cylinder, vector analysis of astigmatism, and efficacy and safety indices were compared between the groups at a mean follow-up of one year postoperatively. Results Baseline characteristics were similar between groups, except the transepithelial PRK group had lower cylinder values than the alcohol-assisted PRK group by 0.69D. Regression analysis was used to control for the difference in the cylinder in all outcome parameters. Both groups had similar mean UDVA (p=0.73), CDVA (p=0.98), the proportion of eyes in either group achieved (20/20, 20/25, and 20/30) UDVA (p=0.72, 0.68 and 0.31 respectively) and percentage of eyes lost two lines of CDVA (p=1.0). There was no statistically significant difference between the two groups in regard to both efficacy and safety indices (p=0.55 and 0.67, respectively). Both groups had similar residual SE (p=0.72), the proportion of eyes within ±0.5D of SE (p=0.29), and residual refractive astigmatism (p=0.87). Both groups had similar difference vectors, surgically induced astigmatism, and correction index (p=0.82, 0.10, and 0.26, respectively). However, the transepithelial PRK group had lower target-induced astigmatism (=0.01), higher magnitude of error (ME; p=0.05), and higher angle of error (AE; p=0.02) than the alcohol-assisted PRK group. Conclusion Transepithelial PRK had similar visual and refractive outcomes as alcohol-assisted PRK. This approach was considered as safe and effective as alcohol-assisted PRK in treating patients with low-to-moderate myopia with or without astigmatism.
PubMed: 37123747
DOI: 10.7759/cureus.36872 -
Frontiers in Medicine 2023Laser-assisted keratomileusis (LASIK) is a unique corneal stromal laser ablation method that uses an excimer laser to reach beneath corneal dome-shaped tissues. In... (Review)
Review
Laser-assisted keratomileusis (LASIK) is a unique corneal stromal laser ablation method that uses an excimer laser to reach beneath corneal dome-shaped tissues. In contrast, surface ablation methods, such as photorefractive keratectomy, include removing epithelium and cutting off the Bowman's layer and the stromal tissue of the anterior corneal surface. Dry eye disease (DED) is the most common complication after LASIK. DED is a typical multi-factor disorder of the tear function and ocular surface that occurs when the eyes fail to produce efficient or adequate volumes of tears to moisturize the eyes. DED influences quality of life and visual perception, as symptoms often interfere with daily activities such as reading, writing, or using video display monitors. Generally, DED brings about discomfort, symptoms of visual disturbance, focal or global tear film instability with possible harm to the ocular surface, the increased osmolarity of the tear film, and subacute inflammation of the ocular surface. Almost all patients develop a degree of dryness in the postoperative period. Detection of preoperative DED and committed examination and treatment in the preoperative period, and continuing treatments postoperatively lead to rapid healing, fewer complications, and improved visual outcomes. To improve patient comfort and surgical outcomes, early treatment is required. Therefore, in this study, we aim to comprehensively review studies on the management and current treatment options for post-LASIK DED.
PubMed: 37113611
DOI: 10.3389/fmed.2023.1057685