Zone of Injury
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Zones of Globe Injury are used to classify open- and closed-globe injuries. This classification schema is useful for maintaining a standard for physician-to-physician communication, for prognosticating globe injury outcomes, for clinical research, and for documentation purposes. Zones of injury differ based on whether a patient undergoes an open-globe injury[1] or a closed-globe injury.
Open-Globe Injury
Zone 1 - Cornea and Limbus
Zone 2 - Posterior to limbus to 5mm posterior into sclera
Zone 3 - Posterior to 5mm from the limbus (Note: Zone 3 has been further subdivided by research groups, as either IIIa being 5 to 8 mm posterior to the limbus; and IIIb being > 8mm posterior to the limbus[2], or alternatively Anterior Zone 3 [5 to 10 mm posterior to the limbus] and Posterior Zone 3 [>10 mm posterior to the limbus[3]]
For more information on open globe injuries, please see Ocular Penetrating and Perforating Injuries and Ruptured Globe.
Closed-Globe Injuries
Zone 1- External anterior segment including conjunctiva, sclera and cornea
Zone 2- Internal anterior segment including the lens, zonules and pars plicata
Zone 3- Posterior segment including vitreous, retina, optic nerve, choroid and ciliary body.
For more information about closed-globe injuries, please see Seven Rings of Trauma
Zone of Injury Documentation
When classifying an injury, one always uses the highest zone injury. For example, a corneo-scleral laceration extending to the rectus muscles would be a Zone 3 open-globe injury not a Zone 1, 2, and 3 injury. Again, in a closed globe injury with a conjunctival abrasion, lens dislocation and a retinal detachment, this would be a Zone 3 closed-globe injury, not a Zone 1, 2 and 3 injury.
Multiple studies have shown that Zone 2 and Zone 3 injuries compared to Zone 1 injuries have a worse visual prognosis.[4][5][6][7] In a retrospective study of 310 open globe eyes, most (46%) were zone (Z) 1 injuries with remaining eyes equally distributed between Z2 and Z3. Z1 injury was shown to have much better visual prognosis than Z2 or Z3 injuries. The visual prognosis of Z3 injured eyes was extremely poor with one-third being enucleated. Final visual acuity of no light perception (NLP) was highest in Z3 eyes (26%) compared to 4% in Z1 and 11% in Z2. [8]
Additional research has shown that far-posterior Zone 3 injuries (pZ3, classified as scleral wounds >10mm beyond the limbus) have worse visual and clinical outcomes compared to more anterior Zone 3 (aZ3) injuries.[3] In a retrospective study of 258 Zone 3 open-globe injuries, 161 (62%) were posterior Zone 3. At 3-month follow-up, posterior Zone 3 OGIs were more likely to exhibit no light perception (pZ3: 38%; aZ3: 17%; P < 0.003), lack count fingers vision (pZ3: 72%; aZ3: 43%; P < 0.002), and fail to read a letter on the eye chart (pZ3: 83%; aZ3: 64%; P < 0.001). The visual acuity distribution at 3 months was significantly worse for pZ3 compared with aZ3 injuries (P < 0.004). Similar results were found at final follow-up. Multiple linear regression showed that pZ3 location was independently associated with worse visual acuity (β = 0.29, 95% confidence interval [CI], 0.09-0.50, P < 0.006) in addition to presenting acuity, age, vitreous hemorrhage, uveal prolapse, and afferent pupillary defect. Far posterior wounds injuries were more likely to develop retinal detachments (pZ3: 87%; aZ3: 71%; P < 0.01) and proliferative vitreoretinopathy (pZ3 66%; aZ3 47%; P < 0.03). Patients with pZ3 OGIs were significantly more likely to reach poor anatomic outcome (phthisis, enucleation, need for keratoprosthesis) compared with patients with aZ3 OGI (pZ3: 56%; aZ3: 40%; P < 0.03).
Additional information about eye trauma terminology can be found at Birmingham Eye Trauma Terminology (BETT), which covers descriptions of open- and closed-globe injuries beyond the Zones of injury.
BIBLIOGRAPHY
- ↑ Pieramici DJ, Sternberg P Jr, Aaberg TM Sr, et al. A system for classifying mechanical injuries of the eye (globe). The Ocular Trauma Classification Group. Am J Ophthalmol. 1997;123(6):820-831.
- ↑ Hoskin AK, Fliotsos MJ, Rousselot A, Ng SMS, Justin GA, Blanch R, Colyer MH, Shukla B, Natarajan S, Kuhn F, Sundar G, Woreta FA, Watson SL, Agrawal R; International Globe and Adnexal Trauma Epidemiology Study (IGATES) Ophthalmic Trauma Terminology Consensus Group. Globe and Adnexal Trauma Terminology Survey. JAMA Ophthalmol. 2022 Aug 1;140(8):819-826. doi: 10.1001/jamaophthalmol.2022.2594. PMID: 35862061; PMCID: PMC9305602.
- ↑ 3.0 3.1 Bleicher ID, Tainsh LT, Gaier ED, Armstrong GW. Outcomes of Zone 3 Open Globe Injuries by Wound Extent: Subcategorization of Zone 3 Injuries Segregates Visual and Anatomic Outcomes. Ophthalmology. 2023;130(4):379-386. doi:10.1016/j.ophtha.2022.10.027
- ↑ Lu Y, Armstrong GW. Prognostic Factors for Visual Outcomes in Open Globe Injury. Int Ophthalmol Clin. 2024;64(2):175-185. doi:10.1097/IIO.0000000000000496
- ↑ Pieramici DJ, Au Eong KG, Sternberg P Jr, Marsh MJ. The prognostic significance of a system for classifying mechanical injuries of the eye (globe) in open-globe injuries. J Trauma. 2003 Apr;54(4):750-4.
- ↑ Yalcin Tök O1, Tok L, Eraslan E, Ozkaya D, Ornek F, Bardak Y.Prognostic factors influencing final visual acuity in open globe injuries. J Trauma. 2011 Dec;71(6):1794-800.
- ↑ Vlasov A, Ryan DS, Ludlow S, Weichel ED, Colyer MH. Causes of combat ocular trauma-related blindness from Operation Iraqi Freedom and Enduring Freedom. J Trauma Acute Care Surg. 2015 Oct;79(4 Suppl 2):S210-5.
- ↑ Tu Y, Soni NG, Bauza AM, Zarbin MA, Bhagat N. Characteristics of open-globe eye injuries with respect to zone of injury. British Journal of Medicine and Medical Research. 2014 May; 4(20):3767-77.
