Diagnostics Ocular Trauma Role of ASOCT in Intracorneal Foreign Body Tarun Arora MD, DNB, FICO Tarun Arora MD, DNB, FICO, Vijay Kumar Sharma MS, Rajesh Sinha MD, DNB, FRCS Cornea, Lens and Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi Ocular injury is the commonest reason for emergency intervention in ophthalmology departments worldwide and represents the second most common cause of visual loss 1. Corneal foreign bodies have been reported to be the second most common type of eye injury, comprising approximately 30.8% of ocular injuries 2. The cornea is prone to injury by foreign bodies; approximately 4-7% of ocular injuries in adults and children involve glass. Figure 1: Slitlamp photograph of various intracorneal foreign bodies (a): Glass (b): Metal (c): Organic foreign body insect wing (d): Stone. www. dosonline.org l 41
Diagnostics: Role of ASOCT in Intracorneal Foreign Body Figure 2: ASOCT image of various intracorneal foreign bodies. (a): Glass well delineated with endothelial continuity maintained. (b): Wood seen in the stromal space with adjacent inflammation. (c): Stone foreign body in deep stroma with iris adhesion and posterior shadowing. Figure 3: Patient presenting with intracorneal glass foreign body (a): Slit lamp photograph showing glass within deep stroma (b): ASOCT shows breach in endothelium with glass extending into the anterior chamber (c): Postoperative day 1 clinical photograph with air in anterior chamber. Substances, such as glass (Figure 1a) and sand, are well tolerated without precipitating a reaction. In these cases, the inert foreign body can be left intrastromal with the patient kept on follow up. However when glass foreign body is in visual axis 3 or causing inflammation it needs to be removed. We 4 have previously published the role of ASOCT and Pentacam in studying posterior astigmatism induced by foreign body and added that as an indication for removal. Other substances, including metals (Figure 1b), wood, organic substances (Figure 1c) and stone (Figure 1d) are poorly tolerated leading to localized edema, inflammatory reaction, opacification, vascularization, and stromal necrosis. Such foreign bodies warrant prompt removal 5. ASOCT is a non-contact method of anterior segment imaging. Higher resolution (5 μm) and faster speed of 42 l DOS Times - Vol. 20, No. 8 February, 2015
Ocular Trauma Figure 4: Patient presented with intracorneal wood foreign body. (a): Slit lamp photograph at presentation (b): ASOCT showing lamellar entry and moderate reflectivity with continuous endothelium. (c): Photograph after removal of wood (d): Postoperative ASOCT showing no evident corneal thinning. A-scan (26,000 scan/ sec) can be obtained with the 840- nm spectral domain OCT (RTVue-100; Optovue, Inc., Fremont, CA) as compared to the 1,310-nm time domain OCT 6,7. In ocular trauma, AS-OCT results can be used to support diagnosis of ocular surface injuries and monitor the healing process after surgical repair. In addition, it may reveal unexpected lesions that are invisible or difficult to recognize on routine slit-lamp examination 8. ASOCT allows non-invasive, rapid imaging of various depths into ocular tissue and therefore provides accurate measurements of foreign body location, number and dimensions. Different reflectivity is appreciable depending on the nature of foreign body. Glass foreign body is well delineated on ASOCT (Figure 2a) with no internal reflectivity. Wood foreign body (Figure 2b) showed moderate internal reflectivity while metal and stone (Figure 2c) foreign bodies showed high anterior reflectivity with shadowing. Endothelial continuity may not be appreciable in such cases. However reflectivity in the anterior chamber 10 or iris adhesion to the site of entry (Figure 2c) may suggest penetration into anterior chamber. The location of the intracorneal foreign body and the status of the surrounding ocular structure dictate which surgical technique should be employed 9. In the past, Au et al 11 described the removal of a corneal foreign body through a lamellar corneal pocket. A lamellar dissection was extended centrally toward the corneal foreign body and the wound was closed with a circumferential mattress suture of 10-0 nylon. This technique was used as the original entry of the foreign body had healed and epithelialized. ASOCT provides vital detail about status of DM integrity and site of entry of foreign body. This information can be utilized to plan the surgical removal. In one such case (Figure 2a), the DM was intact and the scar at the site of entry was appreciable. Hence foreign body was retrieved through the anterior route. However in another case (Figure 3) with trauma with glass foreign body, DM was breached and the entry site had healed. Therefore foreign body could be easily retrieved through the anterior chamber followed by an air tamponade. No sutures were required in that scenario preventing any astigmatic effect. As ASOCT allows the exact determination of location of foreign body along with status of surrounding ocular structures, surgical planning can be performed preoperatively (Figure 4). This prevents any intra or postoperative surprises, thus providing best possible outcomes. www. dosonline.org l 43
Diagnostics: Role of ASOCT in Intracorneal Foreign Body Figure 5: Patient presented with pain after removal of intracorneal foreign body (a): Slit lamp photograph at presentation showing inferior corneal thinning with adjacent edema. (b): ASOCT reveals baring of descemet membrane. Figure 6: Three dimensional ASOCT reconstruction to observe the penetration of intracorneal foreign body through the Descemet membrane. In certain cases, corneal thinning might be suspected after removal of foreign body. ASOCT is extremely advantageous in such situations (Figure 5) as it gives quantitative assessment of remnant corneal thickness and hints the risk of impeding perforation. Cyanoacrylate glue and bandage contact lens can be performed in such cases if the defect is less than 2 mm in dimensions. Future research: ASOCT can be used to prepare highquality cross-sectional and 3D images of the anterior segment. Currently we are exploring the potential of 3D reconstruction ASOCT technology (Figure 6) in managment protocol of intracorneal foreign body. Conclusions Most injuries are mild and do not cause significant ocular morbidity or loss of work. The majority of corneal foreign bodies can be prevented by appropriate eyewear. Anterior segment optical coherence tomography (AS-OCT) is a valuable tool in the early diagnosis and monitoring of treatment progress in cases of ocular trauma. References 1. Mannis MJ, Fiori CE, Krachmer JH et al. Keratopathy associated with intracorneal glass. Arch Ophthalmol 1981; 5: 850 52. 2. Saar I, Raniel J, Neumann E. Recurrent corneal oedema following late migration of intraocular glass. Br J Ophthalmol 1991;3:188 89 3. Huda A. Al-Ghadeer, Abdullah Al-Assiri. Identification and localization of multiple intrastromal foreign bodies with anterior segment optical coherence tomography and ocular Pentacam. Int Ophthalmol. 2014;34:355 8. 4. Arora T, Arora S, Sinha R. Management of intrastromal glass foreign body based on anterior segment optical coherence tomography and Pentacam analysis. Int Ophthalmol. 2014 Dec 19. 44 l DOS Times - Vol. 20, No. 8 February, 2015
Ocular Trauma 5. SmolinG, Thoft RA. The Cornea Scientific Foundation and clinical practice. Little, Brown and Company, New York, pp 1994; 605 633 6. Wylegala E, Dobrowolski D, Nowińska A, Tarnawska D. Anterior segment optical coherence tomography in eye injuries. Graefes Arch Clin Exp Ophthalmol. 2009;247:451 5. 7. Maeda N. Optical coherence tomography for corneal diseases. Eye Contact Lens. 2010;36:254 9. 8. McGwin G, Owsley C. Incidence of emergency department-treated eye in the United States. Arch Ophthalmol. 2005;123:662 6. 9. Hersh PS, Zagelbaum BM, Kenyon KR, Shingelto BJ. Management of anterior segment trauma. In: Tasman W, Jaeger E (eds) Duane s ophthalmology. Lippincott Williams and Wilkins, Philadelphia, 1995; pp 1 19. 10. Goel N, Pangtey BP, Raina UK, Ghosh B. Anterior segment optical coherence tomography in intracorneal foreign body. Oman J Ophthalmol. 2012;2:131-2. 11. Au YK, Libby C, Patel JS Removal of a corneal foreign body through a lamellar corneal pocket. Ophthalmic Surg Lasers 1996;6:471 72. NOTICE The General Body Meeting of Delhi Ophthalmological Society will be held on Sunday the 12th April, 2015 at 4:30 PM at Banquet Hall, Ashok Hotel, Chanakyapuri, New Delhi. The Agenda of the General Body Meeting shall be: 1. Confirmation of the minutes of the previous Annual General Body Meeting held on 24th August, 2014. 2. Adoption of the annual report of executive committee presented by Hony. Secretary. 3. Report of Library officer. 4. Report of Editor DJO. 5. Report from Representative to AIOS. 6. Ratification of New Members. 7. Presentation of Awards and Momentoes. 8. Announcement of election results. 9. Address of the outgoing President. 10. Installation of incoming President. 11. Address of incoming President. 12. Suggestions & Resolutions for General Body Meeting. 13. Any other matter with the permission of the Chair. 14. Vote of thanks by Secretary. All members are requested to attend. Thanking you, Sincerely yours, Dr. Rajendra Khanna President, DOS Dr. Rajesh Sinha Secretary, DOS www. dosonline.org l 45