Ocular Findings in Volcanic Fog Induced Conjunctivitis

Abstract

Objective

To describe the ocular signs and symptoms of patients complaining of eye irritation due to volcanic fog (vog).

Methods

The study utilized a non-comparative, retrospective chart review of 30 patients who had a chief complaint of eye irritation, which the subjects attributed to vog. Ocular signs and symptoms are described and related to the ambient concentration of sulfur dioxide (SO₂), particulate matter sized 2.5 microns (PM_2.5), and vog visibility in O‘ahu during the period of the study.

Results

Ocular signs noted were conjunctival injection (100%), clear mucous discharge (100%), papillary reaction (100%), punctal edema (80%), eyelid swelling (73.3%) and chemosis (63.3%). Ocular symptoms were itchiness (100%), foreign body sensation (100%), tearing (96.6%) and burning sensation (90%). All patients had concurrent respiratory symptoms. During the period of study, the highest 24-hour average concentration of particulate matter sized 2.5 microns (PM_2.5) was 49.04 µg/m³ and vog was visually present.

Conclusions

Patients complaining of eye irritation due to vog have observable ocular signs and symptoms.

Introduction

The word “vog” is a portmanteau of the words “volcanic” and “fog”. Vog is composed of a variety of chemical species including sulfur compounds and particulate matter. The chemicals in vog that cause respiratory and eye irritation are sulfuric oxide gases, sulfate aerosols such as H₂SO₄, NH₄HSO₄, and (NH₄)₂SO₄.^1–3 Vog is also composed of finely sized particles (PM_2.5) of sulfuric acid aerosols, sodium sulfate, and ammonium sulfate.^4,5 Concerns have been expressed regarding the possible health effects of long-term exposure to vog.⁶ Mount Kilauea, currently the world's most active volcano, is the largest source of sulfur dioxide gas (SO₂) in the United States. It has been continuously erupting for 28 years with SO₂ emissions as high as 3000–5000 tons per day.⁷ Most reported health effects attributed to vog are respiratory illnesses.⁸ Its ambient concentration is associated with increased emergency room visits.⁹ Vog has also been shown to statistically increase the odds of developing cardiorespiratory health problems.¹⁰ To the author's knowledge, no reports of the eye findings due to vog exposure have been published.

Methods

In this non-comparative case series, the investigators reviewed charts of 45 consecutive patients seen between January 3, 2011 and March 31, 2011. All patients had a chief complaint of eye irritation attributed to vog and had resided on the island of O‘ahu in Hawai‘i for at least 7 years. Patients who had infectious conjunctivitis, allergies, nasolacrimal duct obstruction, and other ocular conditions (including blepharitis, pterygium, subconjunctival hemorrhage, anterior uveitis, and dry eye) were excluded. Patients on topical eye medications were also excluded. Thirty patients (20 women and 10 men) qualified to be included in the study. Ages of patients ranged from 18 to 85 years (mean 62.8 years). With slit lamp examination, ocular surface findings for both eyes of each patient were tabulated along with the presenting eye symptoms.

Ambient concentrations of sulfur dioxide (SO₂) and particulate matter (PM_2.5) on the island O‘ahu were obtained from the Clean Air Branch of the Department of Health of Hawai‘i. Twenty-four-hour average levels of SO₂ and PM_2.5 were computed and compared to the US Environmental Protection Agency's (EPA) Federal Primary Standard. The University of Hawai‘i Committee on Human Studies approved the research proposal prior to the conduction of the study (CHS-19283).

Results

All patients (100%) had bilateral conjunctival injection and clear mucous discharge. Papillae, a collection of lymphocytes and plasma cells on the conjunctiva, were noted in all patients (100%). The punctum, which is the opening of the lacrimal drainage system, was found to be edematous in 24 patients (80%). Eyelid swelling was found in 22 patients (73.3%). Nineteen patients (63.3%) had bilateral chemosis, which is the accumulation of fluid beneath the conjunctiva. These ocular signs are listed in Table 1. The ocular symptoms are listed in Table 2. All 30 patients (100%) had eye itchiness and foreign body sensation, while 29 patients (96.6%) complained of tearing and 27 patients (90%) had an ocular burning sensation.

Table 1.

Ocular signs in Vog Induced Conjunctivitis (VIC)

Signs	N (patients)/30	N (eyes)/60	(%)
Conjunctival injection	30	60	100%
Papillary reaction	30	60	100%
Clear mucous discharge	30	60	100%
Punctal edema	24	48	80%
Lid swelling	22	44	73.3%
Chemosis	19	38	63.3%

Table 2.

Ocular symptoms in Vog Induced Conjunctivitis (VIC)

Symptoms	N (patients)/30	N (eyes)/60	(%)
Itchiness	30	60	100%
Foreign body sensation	30	60	100%
Tearing	29	58	96.6%
Burning sensation	27	54	90%

Figure 1a shows conjunctival injection while Figure 1b shows excessive tearing, made evident with fluorescein dye. Figure 2a shows an everted upper eyelid with papillae on the palpebral conjunctiva while figure 2b shows papillae and punctal edema of the lower eyelid.

Figure 1.

Conjunctival injection (A). Excessive tearing made evident with fluorescein dye (B).

Figure 2.

Papillary reaction on upper palpebral conjunctiva (A). Papillary reaction on lower palpebral conjunctiva with punctal edema (B).

Ambient levels of PM_2.5 recorded for January (Figure 3a), February (Figure 3b) and March (Figure 3c) from the Honolulu, Pearl City, Kapolei and Sand Island monitoring stations were tabulated. The 24-hour average concentration of PM_2.5 measured had a high of 49.04 µg/m³ and a low of 1.5 µg/m³. Vog visibility was frequent during the study period (Figure 5). Ambient levels of SO₂ recorded for January (Figure 4a), February (Figure 4b), and March (Figure 4c) from the Honolulu, Kapolei, and West Beach monitoring stations showed a 24-hour average concentration high of 0.005 ppm and a low of 0.001 ppm.

Figure 3a.

24-hour average of PM_2.5 levels (µg/m3) measured from O‘ahu monitoring stations, January 2011.

(Data from the Clean Air Branch, Department of Health, Hawai‘i)

Figure 3b.

24-hour average of PM_2.5 levels (µg/m3) measured from O‘ahu monitoring stations, February 2011.

(Data from the Clean Air Branch, Department of Health, Hawai‘i)

Figure 3c.

24-hour average of PM_2.5 levels (µg/m3) measured from O‘ahu monitoring stations, March 2011.

(Data from the Clean Air Branch, Department of Health, Hawai‘i)

Figure 5.

Monthly vog visibility data (January–May 2011).

(Data from the Clean Air Brach, Department of Health, Hawai‘i)

Figure 4a.

24-hour average of SO₂ levels (ppm) measured from O‘ahu monitoring stations, January 2011.

(Data from the Clean Air Branch, Department of Health, Hawai‘i)

Figure 4b.

24-hour average of SO₂ levels (ppm) measured from O‘ahu monitoring stations, February 2011.

(Data from the Clean Air Branch, Department of Health, Hawai‘i)

Figure 4c.

24-hour average of SO₂ levels (ppm) measured from O‘ahu monitoring stations, March 2011.

(Data from the Clean Air Branch, Department of Health, Hawai‘i)

Discussion

Factors affecting deposition of vog on the eyes are airborne concentration, dispersion of aerosols into the atmosphere, and duration of exposure. Vog from Mount Kilauea has been released environmentally in Hawai‘i for more than 28 years, with SO₂ emissions as high as 3000–5000 tons per day.⁷ These emissions are blown from Mount Kilauea to the island of O‘ahu by southwest (Kona) winds, which travel counter to the northeast trade winds. National Oceanic and Atmospheric Administration data show that trade winds are low during the months January to March, which corresponds to the period of the study (Figure 6).¹¹ During these months, the unopposed Kona winds bring vog from Mount Kilauea to other islands like Maui and O‘ahu. Monitoring stations from Pearl City and Kapolei recorded PM_2.5 levels above the 35 µg/m³ 24-hour average standard (Figure 3a). In addition, recorded vog visibility in O‘ahu was high during the period of study (Figure 5). Chronic exposure to environmental toxins is defined as multiple exposures occurring over 7 years, which was the standard used in this study. Since 100% of the patients in the study complained that their eye symptoms were due to vog exposure, and all of the common eye conditions that could cause similar signs and symptoms were excluded, the postulate of this study was that the documented significant levels of vog in the atmosphere were responsible for them.

Figure 6.

Mean monthly frequency of the Trade winds over Hawaiian waters. (Data from the National Weather Service of the National Oceanic and Atmospheric Administration)

The investigators hypothesize that the ocular signs and symptoms described are caused by an amalgam of toxic and allergic reactions. Sulfur dioxide oxidizes to aerosols of sulfuric acid and sulfate compounds forming finely sized particulate matter (PM_2.5).¹² These aerosols irritate the nerves and mucosa of the ocular surface causing tearing and irritation. Particulate matter may also trigger an allergic cascade, stimulating release of histamine. Eye redness and conjunctival injection result from vasodilation and increased blood flow. Chemosis, which is a build up of fluid underneath the bulbar conjunctiva, results from extravasation of plasma. Conjunctival inflammation gives rise to a papillary reaction, which is a fine mosaic pattern of dilated, telangiectatic blood vessels. Papillae are usually seen on the upper palpebral conjunctiva and predispose the eye to a foreign body sensation. Eyelid swelling results as the inflammation becomes more diffuse. Accumulation of particulate matter in the punctum contributes to punctal edema and exacerbates tearing. Itchiness results from the histamine released after the allergic cascade has been triggered. The toxic irritation of sulfuric acid aerosols on the cornea leads to an ocular burning sensation. All of the patients in the study complained of respiratory symptoms consistent with the described allergic manifestations of this condition. Treatment was mainly supportive. Patients were instructed to use ice compresses for ten minutes, 3–4 times a day, and prescribed topical anti-histamine eye drops until symptoms receded. More severe cases were treated with topical steroid eye drops for one week and then switched to topical anti-histamine eye drops.

The investigators propose the term “Vog Induced Conjunctivitis” (VIC) for the constellation of signs and symptoms described in this ocular condition. The description of the signs and symptoms of VIC in this study should allow for the prompt diagnosis of the condition and referral to an eye specialist.

Disclosure Statement

The Authors have no propriety or commercial interest in any materials discussed in this article.