Modification of classification of ocular chemical injuries

Amniotic membrane transplantation for acute ocular burns

BACKGROUND

Ocular surface burns can be caused by chemicals (alkalis and acids) or direct heat. One effect of the burn is damage to the limbal epithelial stem cells of the ocular surface with delayed re-epithelialisation, stem cell failure, and conjunctivalisation of the cornea. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) following an ocular surface burn is claimed to reduce pain and accelerate healing. The surgery involves securing a layer of amniotic membrane (AM) to the eyelid margins as a patch to cover the entire ocular surface. However, there is debate about the severity of an ocular burn that may benefit from AMT and uncertainty of whether AMT improves outcomes.

OBJECTIVES

To compare the effect of AMT with medical therapy in the first seven days after an ocular surface burn, compared to medical therapy alone.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2021, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the WHO ICTRP. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 29 September 2021.

SELECTION CRITERIA

We included randomised trials that compared an AMT applied in the first seven days following an ocular surface burn in addition to medical therapy with medical therapy alone. The outcome measures were failure of re-epithelialisation by day 21 post injury, visual acuity at final follow-up, corneal neovascularisation, symblepharon, time to re-epithelialisation and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, assessed the included studies for risk of bias and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate.

MAIN RESULTS

We analysed two RCTs, but excluded individual patients who had been treated outside the acute phase in one of the studies (data provided by study authors). In total, 36 moderate burns from one RCT and 92 severe burns from two RCTs were evaluated separately. For both categories, the certainty of the evidence was downgraded principally as a result of high risks of performance and detection biases, and because of imprecision indicated by very wide confidence intervals. In addition, follow-up was insufficiently frequent to calculate time-to-epithelialisation precisely. Moderate severity ocular burns (Roper-Hall classification II-III) The relative risk of AMT on failure of epithelialisation by day 21 was 0.18 (0.02 to 1.31), and LogMAR visual acuity was 0.32 lower (0.55 to 0.09 lower) in the treatment group (i.e. better), suggesting a possible benefit of AMT. The GRADE assessment for failure of epithelialisation by day 21 was downgraded to very low due to the risk of bias and imprecision (very wide confidence intervals including no effect). The GRADE assessment for visual acuity at final follow-up was downgraded to low due to the risk of bias and imprecision (optimal information size not met). The relative effects of AMT on corneal neovascularisation (RR 0.56; 0.21 to 1.48), symblepharon (RR 0.41; 0.02 to 9.48) and time-to-epithelialisation (13 days lower; 26.30 lower to 0.30 higher) suggest possible benefit of AMT, but the wide confidence intervals indicate that both harm and benefit are possible. GRADE assessments for these outcomes were once again downgraded to very low due to the risk of bias and imprecision. Since adverse effects are rare, the small sample would have fewer occurrences of rare but potentially important adverse effects. The GRADE assessment for adverse effects was therefore considered to be low.  Severe ocular burns (Roper-Hall classification IV) The relative risk of AMT on failure of epithelialisation by day 21 was 1.03 (0.94 to 1.12), and LogMAR visual acuity was 0.01 higher (0.29 lower to 0.31 higher) in the treatment group (i.e, worse), indicating no benefit of AMT. GRADE assessments for failure of epithelialisation by day 21 and final outcomes were downgraded to low. The relative effects of AMT on corneal neovascularisation (RR 0.84; 0.66 to 1.06), symblepharon (RR 0.89; 0.56 to 1.42) and time-to-epithelialisation (1.66 days lower; 11.09 lower to 7.77 higher) may include both benefit and harm. GRADE assessments for corneal neovascularisation, symblepharon and time-to-epithelialisation were downgraded to low due to risk of bias and imprecision. For adverse effects, the GRADE assessment was downgraded to low, reflecting the small sample sizes in the RCTs.

AUTHORS' CONCLUSIONS

There is uncertain evidence to support the treatment of moderate acute ocular surface burns with AMT in addition to standard medical therapy as a means of preventing failure of epithelialisation by day 21, improving visual outcome and reducing corneal neovascularisation, symblepharon formation and time-to-epithelialisation. For severe burns, the available evidence does not indicate any significant benefit of treatment with AMT.

Advances and Current Clinical Applications of Anterior Segment Optical Coherence Tomography Angiography

Optical coherence tomography angiography (OCTA) is the most relevant evolution based on optical coherence tomography (OCT). OCTA can present ocular vasculature, show detailed morphology for assessment, and quantify vessel parameters without intravenous dye agent. Research on the anterior segment OCTA (AS-OCTA) is only in its initial phase, and its advances in clinical diagnosis and treatment efficacy evaluations require a detailed comparison to traditional imaging methods. In this review of AS-OCTA, we summarize its technical features, imaging advances, current clinical applications in various eye diseases, as well as its limitations and potential future directions. AS-OCTA offers potential advantages in ophthalmic imaging, and with further development it could become a common tool in the near future.

Role of anterior segment optical coherence tomography angiography in assessing limbal vasculature in acute chemical injury of the eye

PURPOSE

To study the role of two anterior segment optical coherence tomography angiography (AS-OCTA) systems in eyes with acute chemical injury.

METHODS

Prospective study in subjects with unilateral chemical injuries. Sequential slit-lamp assessment with spectral domain (SD) (AngioVue, Optovue, USA) and swept source (SS) (Plex Elite, Zeiss, Carl Zeiss Meditec, Dublin, California, USA) AS-OCTA was performed in both eyes within 24-48 hours of injury. Subjects were managed with a standard clinical protocol and followed-up for 3 months. We assessed limbal disruption (loss of normal limbal vessel architecture), limbal vessel density measurements and agreement (kappa coefficient, κ) between masked assessors of limbal disruption based on AS-OCTA scans and slit-lamp assessment.

RESULTS

Ten subjects with median age 31 (25-33) years, 20% women, 60% suffered alkali injuries (Roper-Hall grade 1.5±0.7, Dua grade 2.3±1.2) at presentation. Mean limbal vessel density was lower in quadrants of affected eyes compared with controls detected by SD AS-OCTA (9.4%±2.0% vs 15.5%±1.8%, p<0.001) and SS AS-OCTA (8.8%±2.5% vs 13.9%±1.3%, p=0.01). There was substantial agreement when assessing limbal disruption on AS-OCTA (κ=0.7) compared with slit-lamp evaluation (κ=0.4). Overall, we found good agreement between SD and SS AS-OCTA systems in assessing limbal vessel density in eyes with chemical injury at presentation (mean paired difference: -1.08, 95% CI -3.2 to 0.5; p=0.189).

CONCLUSIONS

In this pilot study, AS-OCTA provided objective, non-contact, rapid assessment of limbal vasculature involvement in eyes with acute chemical injury. Further studies are required to establish the role of AS-OCTA in determining the prognosis of eyes with chemical injury.

Assault-related severe ocular chemical injury at a London ophthalmic referral hospital: a 3-year retrospective observational study

OBJECTIVES

To understand the incidence, causes, management and outcomes of intentional (assault) and unintentional severe ocular chemical injuries (SOCI) at an urban tertiary referral centre in the UK.

DESIGN

Retrospective observational study.

SETTING

A London tertiary referral ophthalmic centre, Moorfields Eye Hospital.

PARTICIPANTS

All cases of SOCI presenting between 1 September 2011 and 31 August 2014 were identified. The definition of SOCI was grade 3 or 4 on the Hughes-Roper-Hall classification system. We identified 25 cases (6 in 2011-2012, 8 in 2012-2013, 11 in 2013-2014). Median age was 31.1 years. 23 cases (92%) were male.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the proportion of cases of SOCI caused by assault, per year. Secondary outcome measures included the number of cases of SOCI, injury characteristics and mechanism, initial and long-term management, visual outcome and the need for surgical intervention.

RESULTS

Between 2011 and 2012, 3/6 cases were due to assault (50%); between 2012 and 2013, 7/8 were due to assault (87.5%); and between 2013 and 2014, 6/11 were due to assault (54.4%). Assault was responsible for 16/25 (64%) cases overall, while 8/25 (32%) cases were work related. The causative agent was known to be alkali in 16/25 (64%), while 10/25 (40%) did not complete the follow-up. The mean number of clock hours of limbal ischaemia was 5.24 (SD 2.97). 17/25 (68%) were Hughes-Roper-Hall grade 3. Surgical intervention occurred in 1/25. The final best-corrected visual acuity was 6/12 or worse in 11/25 (44%) and was counting fingers or worse in 4/25 (16%).

CONCLUSIONS

Previous studies found that SOCI had a low incidence and that work-related injuries were the most common cause. Our study demonstrates an increasing incidence of SOCI, which may be accounted for by a rise in assault using corrosive substances. A high number of patients did not attend regularly for follow-up and visual outcomes from these injuries are poor.

Anterior Segment Optical Coherence Tomographic Angiography Assessment of Acute Chemical Injury

PURPOSE

To compare routine clinical examination with optical coherence tomography angiography (OCTA) for the assessment of limbal conjunctival ischemia following a chemical burn.

SETTING

Validity analysis.

METHODS

We assessed 10 participants (15 eyes) with an acute chemical injury. Clinical photographs were used to determine the extent of any limbal conjunctival epithelial defect and ischemia. These were compared with the extent of limbal ischemia identified on OCTA images of the ocular surface. Quantitative and longitudinal analysis using the OCTA software were also performed. Correlations with visual outcome were sought using clinical and OCTA-derived variables.

RESULTS

The extent of clinically determined limbal ischemia was less than that identified with OCTA (2.3±3.6 clock hours vs 5.1±4.2 clock hours, P = .003), which in turn was less than the size of limbal conjunctival epithelial defect (7.3±5.1 clock hours, P = .03). Longitudinal OCTA analysis showed that mean vessel area increased by 0.2%±0.1% during the study, corresponding to a rate of vascular recovery of 0.9 mm²/d. Significant correlations were found between visual outcome at 3 months and limbal conjunctival fluorescein staining (r = 0.67, P = .006), and limbal conjunctival ischemia on OCTA (r = 0.76, P = .001).

CONCLUSIONS

OCTA can objectively identify and monitor the recovery of limbal ischemia following an acute ocular chemical injury. OCTA confirms that limbal ischemia is usually more extensive than is suggested by clinical examination, and the former is highly correlated with visual outcome. OCTA therefore is a useful tool in the management of ocular chemical injury.

Acute Chemical Eye Injury and Limbal Stem Cell Deficiency-A Prospective Study in the United Kingdom

PURPOSE

To analyze the incidence, nature, outcomes, and complications of acute chemical eye injuries, including the incidence of limbal stem cell deficiency (LSCD) and to compare the 2 main classifications for ocular chemical injuries: Roper-Hall (RH) and Dua.

METHODS

This is a prospective, consecutive, interventional single-center study between April and October 2009 of all new patients with acute chemical eye injury presenting to the Royal Victoria Infirmary eye emergency department (EED).

RESULTS

Of 11,683 patients who attended the EED, 98 patients (110 eyes) presented with acute chemical eye injury (60% male). This represents an estimated annual incidence of 5.6 new cases per 100,000 population. Mean age was 36.5 years (1-78; SD 17.1 years), including 7 children (age <10 years). Fifty-one patients (52%) had work-related injuries. The most common chemical agent was alkali (78%). All 4 RH grade IV cases were unilateral, assault with ammonia, and required early amniotic membrane transplantation as per the protocol, but despite full treatment, they developed total LSCD in the affected eye.

CONCLUSIONS

Acute chemical eye injuries are rare. Male patients in the working age group are more prone to work-related chemical injuries, whereas young children tend to have domestic injuries. Grade I, II, and III RH and Dua chemical injuries had a very good prognosis with topical treatment only, whereas RH grade IV (Dua grade IV-VI), mainly assaults with ammonia, progressed to total/severe LSCD despite appropriate management including early amniotic membrane transplantation. The Dua classification includes conjunctival involvement, having a greater value in predicting the final clinical outcome when grading chemical eye injuries.

Comparative efficacy of two different topical povidone-iodine 5% regimens in reducing conjunctival bacterial flora: A randomized parallel double-masked clinical trial

INTRODUCTION

The increasing prevalence of multi-resistant bacteria is a major public health concern. Infections acquired during ophthalmic surgery are devastating. The purpose of the current study is to compare the proportion of eyes with negative bacterial cultures on all tested media after 1 versus 3 sequential drops of povidone-iodine (PI) 5% into the inferior conjunctival fornix.

METHODS

Patients were randomly assigned to receive 1 (PI group) drop (at time 28 minutes) or 3 (PI plus group) sequential drops (at time 0, 20 minutes and 28 minutes) of PI 5% into the inferior conjunctival sac of one randomly selected eye. A swab culture was obtained from the inferior conjunctival fornix 5 minutes before and 30 minutes after time 0. Central corneal thickness (CCT) was measured shortly before time 0 and shortly after time 30. Conjunctival swabs were incubated aerobically in enriched Thioglycolate liquid medium (meat broth) and in three solid culture media (chocolate agar, trypticase soy agar with 5% sheep blood, and Sabouraud agar).

RESULTS

There was no significant difference in the proportion of negative cultures after intervention between groups (p = 0.1638). Also in the PI group (n = 59), the proportion of eyes with negative cultures after PI (79.7%) did not differ significantly from baseline (76.3%; p = 0.7539). However in the PI plus group (n = 61), the proportion of eyes with all negative cultures after PI (85.3%) was significantly higher than before PI (70.5%) (p = 0.0177). There was no significant difference in mean CCT before and after the intervention in both groups.

CONCLUSION

Instillation of 3 sequential drops of PI was associated with a significant increase in the proportion of eyes with all negative cultures, while instillation of a single drop of PI was not associated with a significant increase in the proportion of negative cultures. Further study is warranted to determine whether the difference between the PI administration regimens is also associated with differences in the rates of postoperative ocular infections.

Treatment of hydrofluoric acid exposure to the eye

AIM

To review the current evidence of the treatment of hydrofluoric acid (HF) exposure to the human cornea.

METHODS

A comprehensive manual search of the literature was conducted through the Ovid interface to assess the mechanism and efficacy of each irrigator through a variety of clinical cases and experimental studies.

RESULTS

Ocular exposure to HF is extremely damaging to the eye and swift recognition and decontamination with an appropriate agent forms the basis of treatment. Although there are various decontamination solutions that have efficacy against the corrosive action of HF, irrigation with Hexafluorine proved to be the most safe and effective treatment for the eye.

CONCLUSION

In conclusion emergency departments could benefit from the availability of Hexafluorine for the treatment of HF ocular burns in patients.

Demographic and clinical profile of ocular chemical injuries in the pediatric age group

OBJECTIVE

To review the risk factors, management, and visual outcomes of pediatric chemical eye injuries in a tertiary care hospital in North India.

DESIGN

Retrospective hospital-based study.

PARTICIPANTS

Patients aged <16 years with ocular chemical burns.

METHODS

Case records of patients with ocular chemical injury who presented to the Dr. Rajendra Prasad Centre for Ophthalmic Sciences were reviewed over a 5-year period.

MAIN OUTCOME MEASURES

Demographic profile, nature of chemical injury, complications, and visual outcomes after chemical injury.

RESULTS

A total of 134 pediatric patients with a history of ocular chemical burns were seen between March 2006 and March 2011. The mean age of patients at the time of injury was 8.95±4.89 years (range, 1.2-15.5 years); 63.4% were male. Sixty-nine patients (51.4%) belonged to the preschool (0-5 years) age group. Bilateral chemical injuries were seen in 24 patients (17.9%). Lime ("chuna") was the most commonly involved chemical (88, 65.6%) followed by toilet cleaner (20, 14.9%). The mean time between injury and presentation was 68.3 days (range, 1-365 days). Severe (grade 3 and 4) ocular chemical injury was seen in 94 patients (70.1%). Surgical intervention was performed in 114 eyes (85%) in the form of amniotic membrane grafting (n = 78), symblepharon release (n = 56), limbal stem cell transplantation (n = 26), and lamellar keratoplasty (n = 14). The average number of surgeries conducted per patient was 2.3 (range, 1-4). Median visual acuity at final follow-up (mean, 537±354 days) was 3/60.

CONCLUSIONS

Chemical injuries in pediatric patients are more commonly encountered in the preschool age group and are associated with severe visual loss. Alkali injury from bursting of chuna packets was the most common mode of injury in pediatric patients in our study.