Appropriate stage of Descemet membrane removal during donor preparation in deep anterior lamellar keratoplasty.

PURPOSE: To investigate the appropriate surgical stage for Descemet membrane (DM) removal during donor preparation in deep anterior lamellar keratoplasty (DALK). METHODS: This study included 83 corneoscleral buttons that were used for DALK. The donor DM was removed randomly either before (group 1; 43 eyes) or after (group 2; 40 eyes) trephination. The time required for DM removal was recorded, and the geometric properties of cut buttons were evaluated after trephination. The intraoperative video recordings were reviewed to determine if the dissections were performed at the stroma-DM plane as it was intended. The time needed to remove the DM, the rate of correct dissection at the intended stroma-DM plane, and the roundness and precision of the donor cuts were compared between the groups. RESULTS: The two groups were comparable in donor characteristics, including age, quality of the tissue, and trephination size. Time spent to remove DM was significantly shorter in group 1 (68.9 ± 48.2 s) than group 2 (117.7 ± 52.7 s, P = 0.001). DM stripping was performed incorrectly in 2 corneas (4.7%) in group 1 and in 12 corneas (30%) in group 2 (P = 0.01). No difference was found between the groups in the roundness and precision of donor button cuts. CONCLUSIONS: DM removal before trephination did not detrimentally affect the geometric properties of punched donor tissues. When DM stripping was performed before trephination, the donor tissue was less traumatized and posterior graft surface was more likely to be regular; therefore, it is advisable to remove DM before trephination during donor preparation for DALK.

Configuration of recipient corneal cut after mechanical trephination in keratoconus.

PURPOSE: To determine the roundness of recipient corneal cuts after mechanical trephination and to investigate possible factors that could affect the corneal bed configuration in deep anterior lamellar keratoplasty (DALK). METHODS: This study enrolled 85 eyes with keratoconus that underwent DALK. Recipient corneas were partially trephined using a new, unused, disposable Hessburg-Barron suction trephine. Photographs that best represented the recipient corneal cut were selected, and ImageJ software was used to evaluate the roundness of recipient bed. The effect of potential variables on the roundness of cuts was investigated using the univariate analyses. RESULTS: The mean patient age was 31.0 ± 9.0 years. The mean recipient trephine size was 8.04 ± 0.29 mm (range 7.5-8.50 mm). The recipient cut roundness was 0.922 ± 0.070, varying from 0.78 to 1.0. The roundness of the corneoscleral limbus (0.874 ± 0.074) which represented the shape of recipient cornea was the main predictor of the configuration of recipient cut (r = 0.84, P < 0.001). Other preoperative characteristics investigated were mean keratometry (P = 0.63), keratometric astigmatism (P = 0.18), central corneal thickness (P = 0.64), keratoconus severity (P = 0.37), and trephine size (P = 0.50) that demonstrated no significant associations with the roundness of cut. CONCLUSIONS: The recipient corneal cut after mechanical trephination may not be circular. The roundness of recipient bed was primarily affected by the roundness of corneoscleral limbus, indicating that the shape of recipient cut tends to follow the original shape of the cornea.

Safety and efficacy of autologous serum eye drop for treatment of dry eyes in graft-versus-host disease.

PURPOSE: To evaluate the treatment of autologous serum eye drops (ASED) on dry eyes in patients with graft-versus-host disease (GVHD). METHODS: A retrospective chart review of 35 patients with a history of ocular GVHD following hematopoietic stem cell transplantation that used ASED to alleviate dry eye symptoms was performed. Patients were categorized into three different groups. If patients had available ophthalmic data before and after starting treatment was group 1 (n = 14), had available ophthalmic data after starting treatment in group 2 (n = 10) and had available ophthalmic data before treatment or did not have any data after starting treatment in group 3 (n = 11). Data were collected on patient's age, gender, primary diagnosis, visual acuity and fluorescein corneal staining were collected on individual eyes in order to evaluate the efficacy of the ASED on alleviating dry eye-related signs and symptoms. RESULTS: No adverse ocular effect from the ASED was found in our series (except one fungal keratitis). All patients reported either improvement (55%) or stability (45%) in their ocular symptoms upon the use of ASED. In patients with available data before and after starting treatment, the corneal staining score improved by a median of 1 (p = 0.003) and the LogMAR visual acuity had a non-significant improvement. CONCLUSION: In our study, ASED used by patients with ocular GVHD were both safe and effective. ASED should be considered in patients with GVHD who suffer from dry eyes.

Autologous serum eye drops for the treatment of ocular surface disease.

OBJECTIVE: To examine the evidence for the role of autologous serum eye drops (ASD) in disease of the ocular surface. METHODS: A search of the literature published through May 2014 using PubMed, the ISI Web of Knowledge database, and the Cochrane Library was performed. Qualified articles were selected after review of titles, abstracts, and references. RESULTS: There was a significant improvement in either symptoms or some of the clinical examination findings, including tear breakup time, corneal staining, Schirmer values, and impression cytology in eyes with persistent corneal epithelial defect, graft-versus-host disease, Sjögren- and non-Sjögren-related dry eye disease, limbal stem-cell deficiency, recurrent corneal erosion, superior limbic keratoconjunctivitis, and postrefractive surgery. However, most of the studies were nonrandomized in nature. CONCLUSIONS: Despite the paucity of strong supporting evidence from randomized double-masked clinical studies, there seems to be a trend toward superiority of ASD in alleviating some of the clinical signs and symptoms associated with corneal pathology in a variety of conditions that affect the ocular surface compared with conventional lubricating drops/ointments.

The sustained delivery of resveratrol or a defined grape powder inhibits new blood vessel formation in a mouse model of choroidal neovascularization.

The objective of this study was to determine whether resveratrol or a defined, reconstituted grape powder can attenuate the formation of new blood vessels in a mouse model of choroidal neovascularization (CNV). To accomplish this objective, C57BL/6J mice were randomized into control or treatment groups which received either resveratrol or grape powder by daily oral gavage, resveratrol or grape powder delivered ad libitum through the drinking water, or resveratrol by slow release via implanted osmotic pumps. A laser was used to rupture Bruch's membrane to induce CNV which was then detected in sclerochoroidal eyecups stained with antibodies against intercellular adhesion molecule-2. CNV area was measured using fluorescence microscopy and Image J software. Ad libitum delivery of both resveratrol and grape powder was shown to significantly reduce the extent of CNV by 68% and 57%, respectively. Parallel experiments conducted in vitro demonstrated that resveratrol activates p53 and inactivates Akt/protein kinase B in choroidal endothelial cells, contributing to its anti-proliferative and anti-migratory properties. In addition resveratrol was shown to inhibit the formation of endothelial cell networks, augmenting its overall anti-angiogenic effects. The non-toxic nature of resveratrol makes it an especially attractive candidate for the prevention and/or treatment of CNV.

Ocular trauma resulting in enucleation: A 12-year experience from a large regional institution.

PURPOSE: To review the frequency and cause of traumatic enucleation at the University of Wisconsin. METHODS: A 12-year retrospective chart review (2000-2012) from the University of Wisconsin Hospital and Clinics of patients who underwent enucleation following ocular trauma with specimens submitted to the University of Wisconsin Eye Pathology Laboratory. RESULTS: A total of 188 eyes enucleated following ocular trauma were identified between 2000 and 2012. One hundred eleven (59%) cases had an identifiable mechanism of injury recorded in the medical record and were included in the final analysis. The overall median patient age was 41 years with 83.8% male. Assault was the most common reason for enucleation (n=30, 27.0%) of which 15 (13.5%) cases were related to gunshot wounds. Other causes included outdoor or recreational activities (n = 20, 18.0%), fall (n = 14, 12.6%), non-motor vehicle accidents (n = 6, 5.5%), motor vehicle accidents (n = 15, 13.5%), work-related injury (n = 15, 13.5%), and sports-related injury (n = 11, 10%). CONCLUSION: Assault is the most common cause of traumatic ocular injury leading to enucleation. Gunshot and stab wounds were responsible for the majority of these cases. Men were much more likely to undergo enucleation due to ocular trauma with the exception being that caused by falls, where the rate was nearly equal between men and women.

Presentation of Adult-onset Asthma and Periocular Xanthogranuloma with Intermediate Uveitis and Hodgkin's Lymphoma: A Case Report.

Purpose: To report a case of adult-onset asthma and periocular xanthogranuloma (AAPOX) in a patient with intermediate uveitis and a history of Hodgkin's lymphoma (HL). Case Report: A 51-year-old man with a past medical history of HL presented with blurred vision, asthma, and bilateral yellowish eyelid lesions. The eyelid lesions and asthma appeared 10 years after being diagnosed with HL. Physical examination was significant for multiple subcutaneous and firm eyelid masses in addition to the presence of pre-auricular and submandibular lymphadenopathies. Ophthalmic examination revealed bilateral intermediate uveitis and mild macular edema. Further systemic evaluations, including laboratory testing and imaging, were normal. Excisional biopsy of the eyelid lesions was performed and the histopathologic examination was consistent with the diagnosis of AAPOX. Conclusion: The presence of AAPOX in a patient with intermediate uveitis and history of HL suggests that immunological dysfunction may play a role in the pathogenesis of adult orbital xanthogranulomatous disease.

A Detailed Analysis of Individuals Having Graft Failure After Corneal Transplantation.

PURPOSE: To describe demographic and clinical characteristics of patients with graft failure after keratoplasty, determine the cause of graft failure and outcomes. METHODS: The charts of patients between 2008-2013 in the Cornea Service at Wills Eye Hospital with a history of a corneal transplant before the end of 2012 were retrospectively reviewed. Included were patients who had graft failure after corneal transplantation and had at least one year of follow-up after transplantation. Penetrating keratoplasty (PK) and Descemet's stripping endothelial keratoplasty (DSEK) patients were analyzed separately. RESULTS: A total of 186 eyes of 170 patients with graft failure after a PK (156) or DSEK (30) procedures were identified. The baseline characteristics included 100 female and 70 male patients with an age between 0 and 90 years (median 63 years). At the time of surgery, 38% had three or more systemic diseases and 68% were using three or more systemic medicines. Mean follow up time for PK was nearly four times of DSEK. Only 2 DSEK eyes (7%) underwent a 3rd DSEK graft, while 47 (30%) PK eyes underwent a 3rd PK and 15 (10%) PK eyes underwent more than three PK procedures. CONCLUSIONS: Most DSEK failures occurred in 1st year, while graft failure in PKs is scattered over years. Failure in DSEK is mostly due to graft or surgical risk factors but in PK mostly due to factors in the host. DSEK does not appear to be as affected by the patients' demographic and clinical characteristics as much as PK.

Conjunctivitis: a systematic review of diagnosis and treatment.

IMPORTANCE: Conjunctivitis is a common problem. OBJECTIVE: To examine the diagnosis, management, and treatment of conjunctivitis, including various antibiotics and alternatives to antibiotic use in infectious conjunctivitis and use of antihistamines and mast cell stabilizers in allergic conjunctivitis. EVIDENCE REVIEW: A search of the literature published through March 2013, using PubMed, the ISI Web of Knowledge database, and the Cochrane Library was performed. Eligible articles were selected after review of titles, abstracts, and references. FINDINGS: Viral conjunctivitis is the most common overall cause of infectious conjunctivitis and usually does not require treatment; the signs and symptoms at presentation are variable. Bacterial conjunctivitis is the second most common cause of infectious conjunctivitis, with most uncomplicated cases resolving in 1 to 2 weeks. Mattering and adherence of the eyelids on waking, lack of itching, and absence of a history of conjunctivitis are the strongest factors associated with bacterial conjunctivitis. Topical antibiotics decrease the duration of bacterial conjunctivitis and allow earlier return to school or work. Conjunctivitis secondary to sexually transmitted diseases such as chlamydia and gonorrhea requires systemic treatment in addition to topical antibiotic therapy. Allergic conjunctivitis is encountered in up to 40% of the population, but only a small proportion of these individuals seek medical help; itching is the most consistent sign in allergic conjunctivitis, and treatment consists of topical antihistamines and mast cell inhibitors. CONCLUSIONS AND RELEVANCE: The majority of cases in bacterial conjunctivitis are self-limiting and no treatment is necessary in uncomplicated cases. However, conjunctivitis caused by gonorrhea or chlamydia and conjunctivitis in contact lens wearers should be treated with antibiotics. Treatment for viral conjunctivitis is supportive. Treatment with antihistamines and mast cell stabilizers alleviates the symptoms of allergic conjunctivitis.

A clinicopathologic case study of two patients with pediatric orbital IgG4-related disease.

The purpose of this report is to describe the clinical, radiographica, and histopathologic findings in two pediatric patients with orbital IgG4-related disease.

Conjunctival nodule in rheumatoid arthritis.

Conjunctival nodule is very rarely seen in patients with rheumatoid arthritis. Previously reported cases were associated with the use of methotrexate. Here, we report a conjunctival rheumatoid nodule without such prior treatment. A 49-year-old woman with seropositive rheumatoid arthritis, who was being treated only with oral steroids and hydroxychloroquine, developed diffuse anterior scleritis in the right eye. In addition, examination showed a focal raised yellow/tan conjunctival nodule. The nodule was within the bulbar conjunctiva with no attachments to the underlying tissue, which is different from nodular scleritis. The nodule was not tender on palpation. The patient underwent excisional biopsy of the nodule. Intraoperatively, the lesion was noted to be a firm nodule within substantia propria of the conjunctiva. Hematoxylin-eosin staining of the specimen revealed a central area of necrosis surrounded by palisades of histiocytes. Increased dosage of oral steroid after the biopsy resulted in resolution of the ocular symptoms and signs. In conclusion, rheumatoid nodules may be seen in the conjunctiva even without prior treatment with methotrexate. These nodules may show the severity of the underlying disease and the need for more aggressive treatment.

Glutathione S-transferase expression in benign and malignant eyelid tumors.

Eyelid tumors commonly originate from the skin and its appendages. Environmental toxins and oxidants affect eyelid carcinogenesis. Glutathione S-transferases (GST) are antioxidants that participate in pathogenesis. We investigated GST levels in malignant and benign eyelid tumors in otherwise healthy individuals. We used 57 malignant eyelid biopsies, benign eyelid biopsies, and tissue removed during blepharoplasty and entropion operations culled from pathology archives. Specimens were divided into three groups: malignant lesions, benign lesions and controls consisting of eyelid tissue removed during routine blepharoplasty and entropion surgery. Specimens were immunostained for seven GST (GST-A, GST-P, GST-Z, GST-S, GST-K, GST-O, GST-T) and the intensity of staining was quantified. In the malignant group, GST-O and GST-P staining was less intense than for the control group. In the benign group, the GST-P level was less than for the control group. We found no significant difference between the intensity of staining in malignant and benign groups. Our findings suggest that GST-O and GST-P enzymes may play significant roles in eyelid carcinogenesis.

Small-angle hypertropia in a case of inferior rectus aplasia: an intraoperative surprise.

Introduction: The clinical features of congenital inferior rectus (IR) aplasia are similar to IR paresis/palsy, and they include hypertropia, limitation of downgaze - especially in abduction, incyclotorsion, A-pattern strabismus, and abnormal head posture.Case report: A 22-year-old man presented with a right face turn, small-angle hypertropia (14 prism diopters) in the right eye, and limitation of downgaze that passed the midline; no diplopia was present and supraduction was normal in that eye. Double Maddox rod revealed 12 degrees of incyclotorsion for the right eye. The Titmus test revealed a stereo acuity of 400 seconds of arc. Based on the preoperative clinical findings, a presumptive diagnosis of IR paresis was made and a surgical plan for performing superior rectus muscle recession and IR muscle resection was devised. Intraoperatively, forced duction test was positive in depression. To our surprise, after performing a 4 mm recession of the superior rectus muscle, we found that the IR muscle was absent. We then revised the surgical plan and performed a 6 mm resection and anterior transposition of the inferior oblique (IO) muscle. Post-operatively, the patient was orthophoric in the primary position without diplopia, and his abnormal head posture was significantly improved.Conclusion: The amount of primary position hypertropia and severity of downgaze limitation are not adequate for differentiating congenital IR aplasia from IR paresis/palsy. Orbital imaging including CT, MRI or anterior segment optical coherence tomography (AS-OCT, UBM) is helpful to distinguish these two entities preoperatively.

Topical 0.03% tacrolimus versus systemic mycophenolate mofetil as adjuncts to systemic corticosteroids for preventing graft rejection after repeat keratoplasty: one-year results of a randomized clinical trial.

PURPOSE: To compare the efficacy of topical 0.03% tacrolimus in combination with systemic corticosteroids versus systemic mycophenolate mofetil (MMF) and corticosteroids in preventing corneal allograft rejection after repeat keratoplasty. METHODS: This prospective, randomized clinical trial enrolled 63 consecutive eyes of 63 patients who underwent repeat keratoplasty after a failed penetrating keratoplasty. Group 1 (32 eyes) received MMF orally 1 g twice daily for the first 6 months and then 1 g daily for the next 6 months, and group 2 (31 eyes) received topical 0.03% tacrolimus four times a day for 12 months. All patients were treated with topical and oral corticosteroids postoperatively. The participants were observed closely for signs of graft rejection, and the rates of rejection-free graft survival were calculated and compared between the two groups at postoperative month 12. RESULTS: The groups were balanced in patient's age and risk factors for graft rejection (e.g., original diagnosis, number of previous grafts, and quadrants of corneal vascularization). Endothelial graft rejection occurred in 5 eyes (15.6%) of group 1 and 6 eyes (19.4%) of group 2 (P = 0.75). Irreversible endothelial graft rejection resulting in graft failure occurred in 3 eyes of each group (P = 0.99). The rate of rejection-free graft survival was 84.4% in group 1 and 80.6% in group 2 at postoperative month 12 (P = 0.74). CONCLUSION: Topical 0.03% tacrolimus was as effective as systemic MMF as adjuncts to topical and systemic corticosteroids in reducing endothelial graft rejection with 12 months follow up after repeat keratoplasty.

Approaches toward enhancing survival probability following deep anterior lamellar keratoplasty.

The greatest advantage of deep anterior lamellar keratoplasty over full-thickness corneal transplantation is the elimination of graft failure caused by endothelial rejection. Despite this advantage, a deep anterior lamellar keratoplasty graft can fail because of several factors, such as complications related to the donor-recipient interface, graft epithelial abnormalities, graft vascularization, stromal graft rejection, and recurrence of herpetic keratitis. Increased deep anterior lamellar keratoplasty graft survival is mainly built upon optimization of the ocular surface to provide a hospitable environment for the graft. Any predisposing factors for graft epithelial abnormalities, corneal neovascularization, and preexisting vernal keratoconjunctivitis should be identified and treated preoperatively. Prompt recognition and appropriate treatment of interface-related complications and stromal graft rejection usually result in good anatomic outcomes, with no detrimental effects on vision.

Conjunctivitis: A Systematic Review.

Conjunctivitis is a commonly encountered condition in ophthalmology clinics throughout the world. In the management of suspected cases of conjunctivitis, alarming signs for more serious intraocular conditions, such as severe pain, decreased vision, and painful pupillary reaction, must be considered. Additionally, a thorough medical and ophthalmic history should be obtained and a thorough physical examination should be done in patients with atypical findings and chronic course. Concurrent physical exam findings with relevant history may reveal the presence of a systemic condition with involvement of the conjunctiva. Viral conjunctivitis remains to be the most common overall cause of conjunctivitis. Bacterial conjunctivitis is encountered less frequently and it is the second most common cause of infectious conjunctivitis. Allergic conjunctivitis is encountered in nearly half of the population and the findings include itching, mucoid discharge, chemosis, and eyelid edema. Long-term usage of eye drops with preservatives in a patient with conjunctival irritation and discharge points to the toxic conjunctivitis as the underlying etiology. Effective management of conjunctivitis includes timely diagnosis, appropriate differentiation of the various etiologies, and appropriate treatment.

Characterization of In Vivo Biomechanical Properties in Macular Corneal Dystrophy.

PURPOSE: To measure and compare corneal biomechanics in patients with macular corneal dystrophy (MCD), versus those who underwent penetrating keratoplasty (PK) for MCD, versus normal subjects. DESIGN: Cross-sectional study. METHODS: This study enrolled 24 eyes with MCD, 25 eyes that underwent PK in patients with preoperative diagnosis of MCD, and 28 normal eyes. The ocular response analyzer was used to measure corneal biomechanical properties, including corneal resistance factor (CRF) and corneal hysteresis (CH). Intraocular pressure (IOP) was measured using a Goldmann applanation tonometer, and central corneal thickness (CCT) was measured using an ultrasonic pachymeter. The CCT, CRF, CH, and IOP were compared among the study group. RESULTS: CCT was significantly lower in the MCD group (423 ± 47 mµ) than in the PK group (541 ± 31 mµ; P < .001) and the controls (540 ± 26 mµ; P < .001). Meanwhile, CCT was comparable between the PK and control groups (P = .98). CRF did not differ between the MCD (8.34 ± 2.12 mm Hg) and the PK (8.66 ± 1.66 mm Hg) groups (P = .89); however, both of these groups had lower CRF values than the control (9.76 ± 1.83 mm Hg, P = .02) group. No significant differences were observed among the 3 groups in CH (P = .13). IOP values did not differ between the MCD (11.25 ± 1.69 mm Hg) and PK (12.0 ± 2.67 mm Hg) groups (P = .95); however, the IOP values for both of these groups differed significantly from those of the controls (13.46 ± 2.17 mm Hg; P = .006). CONCLUSIONS: CRF was significantly reduced in MCD and did not return to normal values even after PK. The reduced corneal rigidity could result in underestimating IOP in patients with MCD and in those undergoing PK for this stromal dystrophy.

Peripheral Hypertrophic Subepithelial Opacities of Corneal Grafts After Deep Anterior Lamellar Keratoplasty.

PURPOSE: To investigate possible underlying etiologies of the development of peripheral graft hypertrophic subepithelial opacities (PGHSO) and to evaluate the effects of these opacities on visual outcomes after deep anterior lamellar keratoplasty (DALK). METHODS: This prospective, interventional case series enrolled 29 eyes with keratoconus that underwent DALK and developed PGHSO (group 1). The control group consisted of 32 eyes with keratoconus that underwent DALK during the same period and had a clear graft at the final examination (group 2). Possible underlying risk factors for the development of PGHSO were investigated, and postoperative refractive and topographic outcomes were compared between the 2 study groups. RESULTS: Eyes of group 1 had well-defined elevated peripheral subepithelial opacities of the corneal graft, originating from the donor-recipient junction. The central 4-mm area of the graft was clear in all eyes of this group. Compared with the controls, group 1 had flatter grafts at postoperative month 1 and a longer time interval from surgery to initial suture removal. The 2 study groups were comparable in other investigated factors, including the severity of keratoconus, surgical technique, duration of topical steroid use, and donor quality. No significant differences were observed between the case and control groups in postoperative visual acuity and graft surface regularity. CONCLUSIONS: Graft flattening during the early postoperative period and prolonged time interval from surgery to initial suture removal might be factors predisposing to the development of PGHSO. This complication did not affect postoperative visual outcomes when the central 4-mm area of the graft remained clear.

Goldmann Applanation Tonometer Versus Ocular Response Analyzer for Measuring Intraocular Pressure After Descemet Stripping Automated Endothelial Keratoplasty.

PURPOSE: To evaluate agreement between IOP measured using the ocular response analyzer (ORA) versus using the Goldmann applanation tonometer (GAT) in patients treated by Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This prospective, case-control study comprised 38 normal eyes and 37 post-DSAEK eyes. IOP was measured using the GAT (IOPGAT). The ORA was used to measure corneal biomechanics and cornea-compensated IOP (IOPCC). Corneal hysteresis (CH), corneal resistance factor, and IOP measurements of the 2 groups were compared. Intertonometer agreement was evaluated in each study group using Bland-Altman plots and 95% limits of agreement. Univariate analysis was used to evaluate the effect of independent factors on the difference between the 2 IOP readings (ΔIOP). RESULTS: The IOPCC and IOPGAT readings showed no significant intergroup differences. IOPCC was significantly higher than IOPGAT, with a mean difference of 3.0 ± 3.3 mm Hg in the normal group (P < 0.001) and 4.5 ± 3.1 mm Hg in the DSAEK group (P < 0.001). The 95% limits of agreement for the IOPCC and IOPGAT was between -3.4 and 9.5 mm Hg and between -1.6 and 10.6 mm Hg in the normal and DSAEK groups, respectively. CH (r = -0.57, P < 0.001) and donor thickness (r = 0.81, P = 0.04) were identified as the main predictors of ΔIOP after DSAEK. ΔIOP did not vary significantly with the central corneal thickness or corneal resistance factor. CONCLUSIONS: The IOPGAT and IOPCC were significantly different, which indicates that the GAT and ORA cannot be used interchangeably for measuring IOP after DSAEK. The difference between these 2 measurements was primarily affected by the variations in CH and donor thickness.