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After serial examination documents new decline in acuity and/or visual field, fractionated radiotherapy appears most likely to preserve visual function and is a valid treatment approach for primary orbital ONSM. Tumor enlargement, as determined by serial imaging, may also provide an indication to begin radiotherapy.

The use of split-thickness dermal grafts for successful repair of corneal and scieral defects is reported in 10 patients (11 eyes) who had non-infectious, impending, or overt ocular perforation. In all patients, traditional methods of reconstruction were deemed inappropriate or had already failed. Corneoscieral defects occurred after various operations: pterygium excision, retinal detachment repair, insertion of a keratoprosthesis (Cardona implant) into an opaque, vascularised cornea, and penetrating keratoplasty. Other causes of corneoscieral defects were scleromalacia perforans, idiopathic systemic vasculitis, alkali burn, ocular cicatricial pemphigoid, and band keratopathy with recurrent erosion following intraocular metallic foreign body. We propose the use of split-thickness grafts: (1) when adjacent conjunctiva is inadequate to cover a corneoscieral defect owing to its large size or great depth or to conjunctival scarring from previous operations, injury, or ocular cicatricial pemphigoid; or (2) as an alternative to autogenous grafts such as conjunctiva, cartilage, fascia lata, tibial periosteum, or mucous membrane as well as to homologous scleral and lamellar grafts. Dermal grafts are advantageous in that they are autogenous, non-antigenic, survive on avascular surfaces, and self-epithelialise and, thus, need not be covered by conjunctiva. Furthermore, they are pliable, have excellent tensile strength, provide ample tectile support, and are abundantly available. Dermal grafts are harvested from the dermal bed of the thigh after an epidermal flap is hinged at one end. (BrJ Ophthalmol 1993; 77: 327-331) flap; the patient was fitted postoperatively with a cosmetic scleral shell.3 We report the use of split-thickness dermal grafts in 10 patients with corneoscleral defects for whom traditional methods were thought to be unsatisfactory or had already been attempted and failed. " Methods INDICATIONS FOR DERMAL GRAFTINGIndications for dermal grafts included: (1) small (1-2 mm) corneoscleral perforations, (2) areas of corneoscleral thinning too large or of too great a depth to be covered by other types ofgrafts or by adjacent conjunctiva, and (3) severe conjunctival scarring which precluded mobilisation of a conjunctival flap over the corneal or scleral defect. For the above reasons alternative methods such as cyanoacrylate tissue adhesive and bandage contact lens and other autogenous grafts such as conjunctiva, cartilage, mucous membrane, fascia, and tibial periosteum as well as homologous scleral and lamellar patch grafts were not used. In some patients such grafts were not employed because they were too bulky or did not contain epithelium.9" SURGICAL TECHNIQUE In all 10 patients, split-thickness dermal grafts were harvested from the outer aspect of the thigh using a power-driven Brown dermatome (Fig 1).

The capacity of the corneal epithelium to adapt to hypertonic challenge is dependent on the ability of the cells to upregulate the expression and activity of cell membrane-associated Na-K-2Cl cotransporter1 (NKCC1). Yet, the signaling pathways that control this response during hypertonic stress are still unclear. We studied stress-induced changes in proliferation and survival capacity of SV40-immortalized human (HCEC) and rabbit (RCEC) corneal epithelial cells as a function of (i) the magnitude of the hypertonic challenge, (ii) differential changes in activation of mitogen-activated protein kinase (MAPK), and (iii) the extent of p38MAPK interaction with NKCC1. Cells were incubated in hypertonic (up to 600 mOsm) media for varying time periods up to 24 h. Phosphorylated forms of p44/42, p38, and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) MAPK were immunoprecipitated from cell lysates, and the amount of each activated NKCC1-associated MAPK was evaluated by Western blot/ECL assay. DNA integrity was assessed by electrophoresis in a 2% agarose gel. Cell survival and proliferation were evaluated based on three criteria: protein content, cell count, and the MTT assay. Exposure to media of 325-350 mOsm increased proliferation of HCEC up to 75%, whereas this response was limited to <16% in RCEC. At higher osmolarities, cell proliferation decreased in both species. SAPK/JNK activity increased 150-fold in HCEC and <10-fold in RCEC, while DNA fragmentation occurred only in HCEC. Compared to HCEC, the better RCEC survival rate was associated with higher p38MAPK activity and near complete restoration of p44/42MAPK activity after the first 30 min. In both cell lines, the amount of phospho-NKCC1 that coimmunoprecipitated with phospho-p38MAPK was proportional to the magnitudes of their respective activation levels. However, no such associations occurred between amounts of phosphorylated p44/42MAPK or SAPK/JNK and phospho-NKCC1. Under isotonic conditions, with bumetanide-induced inhibition of RCEC and HCEC NKCC1 activities, p44/42MAPK activity declined by 40 and 60%, respectively. Such declines led to proportional decreases in cell proliferation. Survival of hypertonicity-stressed corneal epithelial cells depends both on p38MAPK activation capacity and the ability of p38MAPK to stimulate NKCC1 activity through protein-protein interaction. The level of NKCC1 activation affects the extent of cell volume recovery and, in turn, epithelial survival capacity.

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The dependence of regulatory volume decrease (RVD) activity on potassium-chloride cotransporter (KCC) isoform expression was characterized in corneal epithelial cells (CEC). During exposure to a 50% hypotonic challenge, the RVD response was larger in SV40-immortalized human CEC (HCEC) than in SV40-immortalized rabbit CEC (RCEC). A KCC inhibitor-[(dihydroindenyl)oxy] alkanoic acid (DIOA)-blocked RVD more in HCEC than RCEC. Under isotonic conditions, Nethylmaleimide (NEM) produced KCC activation and transient cell shrinkage. Both of these changes were greater in HCEC than in RCEC. Immunoblot analysis of HCEC, RCEC, primary human CEC (pHCEC), and primary bovine CEC (BCEC) plasma membrane enriched fractions revealed KCC1, KCC3, and KCC4 isoform expression, whereas KCC2 was undetectable. During a hypotonic challenge, KCC1 membrane content increased more rapidly in HCEC than in RCEC. Such a challenge induced a larger increase and more transient p44/42MAPK activation in HCEC than RCEC. On the other hand, HCEC and RCEC p38MAPK phosphorylation reached peak activations at 2.5 and 15 min, respectively. Only in HCEC, pharmacological manipulation of KCC activity modified the hypotonicity-induced activation of p44/42MAPK, whereas p38MAPK phosphorylation was insensitive to such procedures in both cell lines. Larger increases in HCEC KCC1 membrane protein content correlate with their ability to undergo faster and more complete RVD. Furthermore, pharmacological activation of KCC increased p44/42MAPK phosphorylation in HCEC but not in RCEC, presumably a reflection of low KCC membrane expression in RCEC. These findings suggest that KCC1 plays a role in (i) maintaining isotonic steady-state cell volume homeostasis, (ii) recovery of isotonic cell volume after a hypotonic challenge through RVD, and (iii) regulating hypotonicityinduced activation of the p44/42MAPK signaling pathway required for cell proliferation.

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