Featured Case

MODERN DIAGNOSIS: Ethambutol toxic optic neuropathy

ABOUT THE DISEASE:

Ethambutol (EMB) is an antibiotic used to treat infection by Mycobacterium species, particularly Mycobacterium tuberculosis and non-tubercular infections like M. avium complex and M. kansasii. Unfortunately, one serious and vision-threatening side effect of EMB is ethambutol-induced optic neuropathy (EON). Less common side effects of EMB include peripheral neuropathy, cutaneous reactions, thrombocytopenia, and hepatitis.

Pathogenesis:

Retrobulbar optic neuropathy (normal-appearing optic disc on presentation) is the most common form of EOM. While the exact mechanism of the neurotoxic effect of EMB on the optic nerve is unknown, it is believed that the metal-chelating effects of this drug may be responsible. One theory is that the chelation of copper disrupts oxidative phosphorylation, as there is less copper available in human mitochondria. Another theory is that the chelation of zinc inhibits lysosomal activation. Moreover, in animal studies on rat optic nerves, zinc deficiency has been associated with the destruction of myelin and glial cell proliferation, suggesting that there may be a similar effect in humans. In addition, prolonged EMB use has been shown to be associated with deficiencies in vitamin E and vitamin B1 which may exacerbate optic neuropathy.

Diagnosis: The diagnosis of EON is made clinically with visual acuity, formal perimetry and color vision testing. Fundoscopy is necessary to exclude other aetiologies of visual loss in particular retinal disease. The presence of optic disc oedema or macular pathology would argue strongly against EON. Patients should receive a baseline eye exam prior to initiation of EMB therapy in order to document pre-treatment ocular pathology. Unfortunately unlike other toxic maculopathies (e.g. hydroxychloroquine), there is no pre-toxicity finding in EON for screening. Nevertheless, high-risk patients for EON (e.g., long duration or high dose EMB, renal dysfunction) should have a visual assessment every month and all patients on EMB should have central vision assessment (e.g., visual acuity, Amsler grid) monthly (although this screening does not require a full dilated ophthalmology exam). If vision changes are noticed, the patient should see an ophthalmologist and if there is a suspicion for EON, the treating physician must be contacted in order to make a decision of whether to continue or discontinue EMB therapy. 

Image 1. Perimetry reports dated April 2020 are added below (old reports)

Treatment: Currently, there is no effective treatment for EON. However, if the condition is detected early and the drug is discontinued promptly (before the development of irreversible optic atrophy), between 30-64% of patients have been reported to show visual improvements over a course of several months. However, full recovery is rare, and the average improvement is two lines on the Snellen chart. Older patients, especially those over 60 years of age, have been found to have poorer recovery compared to younger patients.

In this case report, the 75-year-old female patient approached Dr Sreekanth with defective vision in both eyes for 2 years and occasional redness of the eyes. She had been taking Category 1 Anti Tubercular Treatment with topical steroids and cycloplegic drugs - Ethambutol since November 2019. It was in February 2020 that the blurring of vision started. In August 2020, the symptoms worsened and there were floaters in the eye. The Biomedical diagnosis was Ethambutol-induced toxicity, and the ATTs were stopped immediately, and she was put on vitamin supplements. But even in further follow-ups, there were no improvements in the vision. So she opted for Ayurveda.

Prognosis: Most patients who discontinue EMB after the onset of visual changes (without optic atrophy) will recover their vision over weeks to months. The presence of optic disc pallor at the onset of visual symptoms is associated with poor prognosis. In this case, there was optic pallor noted in both eyes. Also, due to the patient’s ignorance, she continued ATT drugs 6 more months even after the onset of blurring. With the initiation of Ayurveda treatments, for 3 months, visual acuity improved in both eyes (RE- 3/60, LE- 3/60), and floaters in RE were reduced.

Reference

Ethambutol optic neuropathy by American Academy of Opthalmology. EyeWiki.

AYURVEDA DIAGNOSIS: Drishtigata Rogam

ABOUT THE DISEASE:

Eye diseases are generally referred to as Netra rogas, and diseases affecting vision are generally referred to as Drishti Rogas.

Susruta explains the shape of drishti with the masoor daal (Lens culinaris) i.e. the biconvex shape of the lens, formed by the finest part of the combination of five basic elements and fire spark or glow-worm-like gleaming in texture, filled with the teja, covered with patalas.

Netra rogas are Raktapradoshaja Vikaras. The Vitiated Doshas in the body move to Urdhvajatru i.e, upper parts of body through the sira and gets sthanasanshraya in netra which results in netraroga. In Ayurveda, the treatment modality like Shodhana Cikitsa i.e, detoxification destroys the complete pathophysiology of the disease. There are 12 drishti roga according to Susruta and 27 according to Vaghbhata. This includes diseases like Timira, nakulandhya, vidagdha drishti, dhumadarshi, hrsvajadhya.

The general explanation of Drishti roga are related to the various layers called patala. They are Prathama, dvitiya, Tritiya and Caturtha patala gata roga. Depending on the patala affected by the disease, the symptoms will vary.

This case report is of a 75-year-old female patient who approached Dr Sreekanth with defective vision in both eyes for 2 years and occasional redness of the eyes. This was attributed to her taking the category 1- antituberculosis drug Ethambutol. The medicine was stopped and she tried conventional medicine for 3 months but did not get relief.

Sadhyasadhyata: Depending upon the drishtigata roga, the sadhyasadhyata varies. But in this case report, the specific type is not mentioned. So the prognosis from the theoretical point of view cannot be mentioned, but this is a chronic condition and was not responding to conventional management. So this can be placed under the category of kricchrasadhya.

Rationale of treatment:  The targets of medicines prescribed for treatment are as follows: Amrtottaram  Kwatha- Ama Pachana and Sroto Sodhana;  ensuring normal digestion to facilitate delivery of proper rasadhatu and nutrients to the eyes and nerves

Bharngyadi Kvatha- Dipana and Pacana karma ensuring a return to normal digestion to facilitate delivery of proper rasadhatu and nutrients to the eyes and nerves.

Trikatu with lime juice, Cough mix, and Fever mix- These medicines were prescribed to alleviate mild fever and cough-like symptoms that the patient developed early in the treatment.

Varanadi Kvatha, Punarnavadi Kvatha- Abolishing the Avarana of Kapha and Vata; re-instigating Vyana Vata to ensure supply of nutrition to the nerve, further enhancing Jatharagni to ensure delivery of properly formed rasadhatu to the eyes and nerves.

Dhanadarasnadi Kvatha- Enhancing the activity of Vyana Vata in the nerves and delivery of essential nutrients and vascular supply to the optic nerve and eyes

Drakshadi Kvatha- Balancing Vata and Pitta in the eyes, enhancing vision and restore neuronal activity

Guggulu Pancapala Tablet- Addressing the Avarana of Kapha and Vata and enabling nutrition to reach the nerves by its Sroto shodhana  property

AsvagandhaTablet- Enhancing the supply and activity of the nerves and eyes by its Balya and Brmhana property

Sudarsana Gutika- Enhancing the Jatharagni, cleansing the srotas, enabling delivery of nutrients and enhancing function to the eyes and nerves.

Patoladi Ghrta- Enhancing vision and strengthening the retina and nerves by its Pitta-Kapha Samana and Sroto shodhana properties.

Agastya Haritaki- -Enhancing nervous supply and nutrition by its Balya and Brmhana properties.

Reference

1. Susruta Samhita. Uttara tantra. 7th Chapter and 17th Chapter.

OUTCOME MEASURES:

A 75-year-old female patient approached Dr Sreekanth with defective vision in both eyes for 2 years and occasional redness of the eyes. She had been taking Category 1 Anti Tubercular Treatment with topical steroids and cycloplegic drugs – Ethambutol (EMB) since November 2019. It was in February 2020 that the blurring of vision started. In August 2020, the symptoms worsened and there were floaters in the eye. The Biomedical diagnosis was Ethambutol-induced toxicity, and the ATTs were stopped immediately, and she was put on vitamin supplements. But even in further follow-ups, there were no improvements in the vision. So she opted for Ayurveda. Dr Sreekanth diagnosed this condition as Drishti gata rogam. The line of treatment followed was pacifying the tridoshas, and improving the agni, ama pacana, sroto shodhana, by administering balya and brmhmana dravya.

Subjective parameters: As on 26/6/2022:

The patient is able to read big letters and write a complete sentence correctly within a line. Colour vision has improved

Floater- Now only one black spot is present.

Redness - No another episode of redness in the eyes.

Patient feels more confident to carry out day-to-day now activities.

After 3 weeks of ayurveda treatment, visual acuity improved in both eyes (RE- 3/60, LE- 3/60), floaters in RE reduced.

Objective parameters:

The topography reports dated 27.1.2022 during treatment are added below