Faculty Bibliography

PURPOSE/OBJECTIVE:To determine the effect of Ultraviolet-A collagen cross-linking with hypo-osmolar and iso-osmolar riboflavin solutions on stromal collagen ultrastructure in normal and keratoconus ex vivo human corneas. METHODS:Using small-angle X-ray scattering, measurements of collagen D-periodicity, fibril diameter and interfibrillar spacing were made at 1 mm intervals across six normal post-mortem corneas (two above physiological hydration (swollen) and four below (unswollen)) and two post-transplant keratoconus corneal buttons (one swollen; one unswollen), before and after hypo-osmolar cross-linking. The same parameters were measured in three other unswollen normal corneas before and after iso-osmolar cross-linking and in three pairs of swollen normal corneas, in which only the left was cross-linked (with iso-osmolar riboflavin). RESULTS:Hypo-osmolar cross-linking resulted in an increase in corneal hydration in all corneas. In the keratoconus corneas and unswollen normal corneas, this was accompanied by an increase in collagen interfibrillar spacing (p<0.001); an increase in fibril diameter was also seen in two out of four unswollen normal corneas and one unswollen keratoconus cornea (p<0.001). Iso-osmolar cross-linking resulted in a decrease in tissue hydration in the swollen normal corneas only. Although there was no consistent treatment-induced change in hydration in the unswollen normal samples, iso-osmolar cross-linking of these corneas did result in a compaction of collagen fibrils and a reduced fibril diameter (p<0.001); these changes were not seen in the swollen normal corneas. Collagen D-periodicity was not affected by either treatment. CONCLUSION/CONCLUSIONS:The observed structural changes following Ultraviolet-A cross-linking with hypo-osmolar or iso-osmolar riboflavin solutions are more likely a consequence of treatment-induced changes in tissue hydration rather than cross-linking.

PURPOSE/OBJECTIVE:To report the effect of corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) on the optical and material characteristics of a posterior chamber phakic intraocular lens (Visian ICL, STAAR Surgical). METHODS:Optical and material characteristics were assessed in vitro, analyzing potential changes in riboflavin staining, dioptric power, transmission characteristics, and surface structure. A total of 9 lenses were analyzed: 3 lenses were irradiated with 0.23 mW/cm², the maximal intensity that may be encountered during actual surgery; 3 lenses were irradiated with 2.3 mW/cm², 10 times the maximal intensity encountered during surgery; and 3 lenses served as controls. RESULTS:Following CXL with UVA and riboflavin, no changes were observed in the parameters tested; in particular, dioptric power and transmission characteristics were similar before and after CXL. CONCLUSIONS:Cross-linking with UVA and riboflavin does not affect the optical and material characteristics of the Visian ICL after irradiation with the maximal UVA energy levels that may be encountered during surgery. Even when the UVA irradiation dose was increased by a factor of 10, no changes were observed.

PURPOSE/OBJECTIVE:To analyze intra- and postoperative variation in Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments) parameters in 24 keratoconic eyes undergoing corneal cross-linking (CXL). METHODS:In a prospective clinical study, corneal hysteresis (CH), corneal resistance factor (CRF), peak 1 and peak 2 amplitude, corneal-compensated and Goldmann-correlated intraocular pressure (IOP) were evaluated using the ORA. The thinnest cornea point was measured with the Pentacam (Oculus Inc). Corneal topography and endothelial cell count were performed. Measurements were recorded at baseline; intraoperatively after epithelium removal, riboflavin impregnation, and ultraviolet A irradiation; and postoperatively after corneal re-epithelialization and at 1, 6, and 12 months. RESULTS:A statistically significant reduction of the thinnest cornea point from 462±23.24 μm was observed at the end of the CXL procedure intraoperatively and at 1- and 6-month follow-up (P<.05). A significant increase in the thinnest cornea point to 624±31.72 μm was found after re-epithelialization (P<.05), and no significant changes were observed at 1 year postoperatively. Mean CH and CRF did not change significantly after de-epithelialization, but were noted to significantly increase after CXL intraoperatively and postoperatively at 1-month follow-up. At 6 and 12 months postoperatively, CH and CRF were not statistically significantly different from pre-operatively. Peak 1 and peak 2 decreased intraoperatively from 276±52 and 228±47 to 172±42 and 131±42, respectively, at the conclusion of CXL (P<.05), and were noted to increase to 493±41 and 444±51, respectively, at 6-month follow-up. Corneal-compensated IOP and Goldmann-correlated IOP increased at 1 month after CXL (P>.05). CONCLUSIONS:The results showed a significant change in ORA parameters and the thinnest cornea point during and after the CXL procedure and a high correlation between peak amplitudes and corneal asymmetry, providing insight to the bioelastic and biomechanical behavior of the cornea during and after CXL.

BACKGROUND:We reviewed the radiologic features of 15 patients with orbital metastases originating from breast cancer. METHODS:This was a retrospective consecutive case series. Fifteen consecutive patients with orbital metastases originating from breast carcinoma were identified between March 1997 and September 2008. A retrospective chart review was carried out, and the radiologic findings were reviewed. RESULTS:The metastases were preseptal in 53%, intraconal in 60%, and both intraconal and extraconal in 33%. Lacrimal gland enlargement was noted in 33%, episcleral space involvement in 33%, bone involvement in 13%, and globe dystopia in 53%. The extraocular muscles were involved in 87%; in 60%, two or more muscles were involved. The medial and lateral rectus muscles were affected in 53% and 47%, respectively, and the inferior and superior rectus muscles in 33%. In 47% one or more radiologic features had not been noted by the radiologist, and in 20% the findings were misinterpreted as an"orbital pseudotumor." CONCLUSION/CONCLUSIONS:Orbital metastases originating from breast cancer may present heterogeneously. Orbital imaging most commonly shows unilateral and multifocal involvement of multiple extraocular muscles and intraconal and preseptal areas by an irregular lesion.

BACKGROUND:Actinidia deliciosa (kiwifruit) is used as a meat tenderizer. It acts rapidly and efficiently to soften meat, liquefying it if allowed to work for more than a few hours. Observing this effect and the lack of studies addressing this subject in the literature, the authors sought to investigate the use of this natural remedy in an animal model for eschar separation and debridement. METHODS:Thirty-five male rats were divided randomly into three groups. Under general anaesthesia, a limited standard full-thickness burn was produced on the back of each rat. For the intervention group (G1, 15 rats), the wounds were covered with fresh kiwifruit; for control groups 2 and 3 (G2, 15 rats; G3, five rats), the dressing was a neutral ointment (Emulsifier 1220). Weekly wound observations were documented for all the groups. G1 and G2 were sacrificed on Day 20, and group 3 was kept alive until complete eschar separation. The wounds of the rats in groups 1 and 2 were excised and subjected to microscopic evaluation. RESULTS:On Day 20, all eschars had detached and fallen off in the intervention group (G1), whereas in groups G2 and G3 the eschars were still firmly attached to the base of the wounds (except in two rats of G2); this finding was statistically significant (p<0.001). The average wound surface area in group G1 was 212 mm(2) (SD=88.80938) whereas in G2 it was 388 mm(2) (SD=140.6967). Thus, the wound surface area was significantly (p<0.001) smaller in the intervention group. The eschars in G3 separated spontaneously between days 30 and 42, while in all the rats of the kiwi-treated group, this phenomenon occurred before Day 20. The pathological study revealed no considerable differences between G1 and G2 (p<0.05). CONCLUSIONS:Debridement and scar contraction occurred faster in the kiwi-treated group than in the untreated group. Following rapid enzymatic debridement, healing appeared to progress normally, with no evidence of damage to adjacent healthy tissue.

BACKGROUND:In most references to the nasal anatomy, the shape of the lower lateral cartilage (LLC) is described as a two-dimensional structure. However, the authors have found different forms of LLC in at least 40% of their open rhinoplasty cases during the past 20 years. This cartilage was found to have a three-dimensional hemispheric appearance and to be connected to the upper lateral cartilage (ULC) at the scroll area by an inward limb of this hemisphere. This inward limb may have an important role in producing asymmetry and flare of the nostril. METHODS:The LLC of 286 patients was evaluated during open rhinoplasty over a 2-year period, with a focus mainly on the shape of this structure, especially at the LLC-ULC junction (scroll area). RESULTS:A dome-shaped appearance of the LLC was noted in 40.9% of cases, and 11.5% of cases had bilateral LLC variation. This different anatomic form was seen mostly in patients with a strong bulbous nasal tip, although it was observed less frequently also in patients with narrow nasal tips. CONCLUSION/CONCLUSIONS:At least one-third of the LLCs analyzed had a medial wall in addition to the lateral wall, which significantly increased the flare and recoil force of this structure. This makes this cartilage more redundant to reshaping procedures (straightening). Thus, special attention must sometimes be paid to this common anatomic variation to produce symmetric nostrils and to obtain a more aesthetically acceptable alar tip.