A histopathologic study of orbital implant vascularization

Ocular Medical Devices: Histologic Technique and Histopathologic Evaluation of the Biocompatibility and Performance

Ocular medical devices (MDs) represent a very wide and promising field of human ophthalmology. In preclinical studies evaluating the safety and/or performance of these ocular MDs, the choice of histologic technique and the focus of the histopathologic evaluation method should take into consideration the following aspects: the specific guidelines possibly associated with the MD or combination product, the ocular compartment in contact with the MD and its specificities, and last the nature of the biomaterial used in the MD. Following a brief overview of animal models, this short review will present the different types of ocular MDs and will present the specificities of the histologic technique and the histopathologic evaluation related to ocular MDs.

Fibrovascular ingrowth into porous polyethylene orbital implants (Medpor) after modified evisceration

PURPOSE

To evaluate, using MRI, the extent and pattern of fibrovascular ingrowth into Medpor implants after modified evisceration.

METHODS

Contrast T1-weighted images were performed in 21 patients within 1.5- to69-month intervals after modified evisceration with primary Medpor implantation. In 6 patients, the images were obtained separately following 1- and 5-minute delays after contrast administration.

RESULTS

No grade I enhancement occurred in these series. Grade II was observed in 2 patients (9.09%), grade III in 8 patients (36.36%), grade IV in 9 patients (40.91%), and grade V in 3 patients (13.64%). Significant correlation existed between the grade of enhancement and the postevisceration interval (r = 0.483, p = 0.023 < 0.05). The images demonstrated an enhancement pattern that started at the unwrapped posterior pole and anterior location of rectus muscles with progressive centripetal vascularization toward the center of the implant. At the early stage of recovery, the fibrous connective tissue was thick in front of Medpor spheres. In the 5-minute delay images of 6 patients, 2 patients failed to exhibit further enhancement; 2 patients exhibited enlarged and homogeneous enhancement; and 2 patients revealed more intense enhancement patterns. The medical ethics committee of Zhongshan Ophthalmic Center approved the study.

CONCLUSIONS

Fibrovascular ingrowth into Medpor implants was satisfactory after the modified evisceration and correlated with the duration of the implants. The double layers of sclera effectively prevented the implant extrusion and exposure. The authors recommend waiting at least 5 minutes before obtaining MR images after contrast administration.

Helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure: A superior option

The aim of the present study was to evaluate the efficacy of helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure and compare the results with those of a combined drugs and surgery regimen. A total of 70 patients with hydroxyapatite orbital implant exposure in 70 eyes were randomly divided into two groups: Helium-neon laser therapy (group A) and drugs plus surgery (group B). Each group contained 35 patients. The healing rates and times of the conjunctival wound were recorded and compared following helium-neon laser treatment or the drugs plus surgery regimen. Changes in the hydroxyapatite orbital implant prior to and following helium-neon laser irradiation were analyzed. A similar animal study was conducted using 24 New Zealand white rabbits, which received orbital implants and were then received drug treatment or helium-neon therapy. In the human experiment, the rates for conjunctival wound healing were 97.14% in group A and 74.29% in group B, with a significant difference between the groups (χ²=5.71, P<0.05). Patients with mild exposure were healed after 7.22±2.11 days of helium-neon laser therapy and 14.33±3.20 days of drugs plus surgery. A statistically significant difference was found between the groups (t=8.97, P<0.05). Patients with moderate to severe exposure were healed after 18.19±2.12 days of helium-neon laser therapy and 31.25±4.21 days of drugs plus surgery. The difference between the groups was statistically significant (t=7.91, P<0.05). Enhanced magnetic resonance imaging showed that the helium-neon laser therapy significantly promoted vascularization of the hydroxyapatite orbital implant. These results, combined with pathological findings in animals, which showed that a helium-neon laser promoted vascularization and had anti-inflammatory effects, suggest that helium-neon laser irradiation is an effective method for treating hydroxyapatite orbital implant exposure, thereby avoiding secondary surgery.

Comparative study of modified and conventional secondary hydroxyapatite orbital implantations

AIM

To compare the clinical effects of the modified and conventional secondary hydroxyapatite orbital implantations.

METHODS

A total of 40 patients who had received eye enucleation were equally randomized into the modified and conventional groups. Twenty patients were treated by conventional method. The four rectus muscles were separated, and then an orbital implant wrapped with xenogenous sclera was implanted. Twenty patients were treated by modified method. An implant unwrapped with xenogenous sclera was directly implanted into the muscle pyramid. The operating time, costs, clinical effects, and complications of the two groups were compared.

RESULTS

The average operating time of the modified group was 20.5±5.6min, whereas that of the conventional group was 56.8±14.6min (P<0.01). The average cost of the modified group was 7 800±340RMB (1 274±55.6USD), whereas that of the conventional group was 9 800±660RMB (1 601±107.8USD) (P<0.01). The two groups did not show significant difference in orbital implant mobility or postoperative complications.

CONCLUSION

The modified secondary hydroxyapatite orbital implantation has advantages in operating time, surgery cost, and complication reducing. It is worthy for wide clinical application and further study.

The psychosocial benefits of secondary hydroxyapatite orbital implant insertion and prosthesis wearing for patients with anophthalmia

PURPOSE

Anophthalmia is associated with a range of psychosocial difficulties and hydroxyapatite orbital implant insertion and prosthesis wearing is the predominant rehabilitation therapy for anophthalmia. However, few articles have compared preoperative and postoperative psychosocial outcomes using standardized questionnaires. This study aimed to investigate the psychosocial benefits of hydroxyapatite orbital implant insertion and prosthesis wearing in this patient population.

METHODS

In all, 36 participants were tested preoperatively and 6-months postoperatively using standardized measures of anxiety and depression (Hospital Anxiety and Depression Scale), social anxiety and social avoidance (Derriford Appearance Scale-Short Form), and quality of life (World Health Organization Quality of Life Scale-Short Form).

RESULTS

Before treatment, levels of depression were comparable with population norms; however, levels of general anxiety were slightly raised, levels of social anxiety, social avoidance, and quality of life were significantly poorer than population norms. Treatment resulted in significant improvement in psychosocial adjustment with improvements in all study variables for the participant group as a whole.

CONCLUSION

Hydroxyapatite orbital implant insertion and prosthesis wearing offers significant improvements in psychological and physical functioning for patients with anophthalmia.