Aldeyra Therapeutics : Corporate Overview

January 2022

CORPORATE OVERVIEW

Innovative Therapeutics

to Treat Immune-Mediated Diseases

Nasdaq: ALDX

© Aldeyra Therapeutics, Inc. 2022

Disclaimers and Forward-Looking Statements

This presentation and various remarks which may be made during this presentation contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and Section 21E of the Securities Exchange Act of 1934, as amended, including statements regarding Aldeyra's possible or assumed future results of operations, expenses and financing needs, business strategies and plans, research and development plans or expectations, political, economic, legal, social and health risks, including the COVID-19pandemic and related public health measures and other responses to it, that may affect Aldeyra's business or the global economy, the structure, timing and success of Aldeyra's planned or pending clinical trials, expected milestones, market sizing, pricing and reimbursement, competitive position, regulatory matters, industry environment and potential growth opportunities, among other things. The results of earlier preclinical or clinical trials may not be predictive of future results. As a result of the COVID-19 pandemic, clinical site availability, staffing, and patient recruitment have been negatively

affected and the timelines to complete Aldeyra's clinical trials may be delayed. Forward-looking statements include all statements that are not historical facts and, in some cases, can be identified by terms such as "may," "might," "will," "objective," "intend," "should," "could," "can," "would," "expect," "believe," "anticipate," "project," "target," "design," "estimate," "predict," "potential," "plan" or similar expressions and the negatives of those terms.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause Aldeyra's actual results, performance or

achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These statements reflect Aldeyra's current views with respect to future events and are based on assumptions and subject to risks and uncertainties, including the development, clinical and regulatory plans or expectations for Aldeyra's product candidates and systems-based approaches, later developments with the FDA that may be inconsistent with Aldeyra's expectations and beliefs, including the risk that the results from earlier clinical trials, portions of clinical trials, or pooled clinical data may not accurately predict results of subsequent trials or the remainder of a clinical trial for the same or different indications, inconsistent expectations regarding FDA acceptance and review of the company's filings and submitted data sets, and Aldeyra's continuing review and quality control analysis of clinical data. Important factors that could cause actual results to differ materially from those reflected in Aldeyra's forward-looking statements are described in Aldeyra's most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q, as well as Aldeyra's subsequent filings with the Securities and Exchange Commission. All of Aldeyra's development plans and timelines may be subject to adjustment depending on funding, recruitment rate, regulatory review, preclinical and clinical results,

and other factors any of which could result in changes to Aldeyra's development plans and programs or delay the initiation, completion, or reporting of clinical trials.

In addition to the risks described above and in Aldeyra's other filings with the SEC, other unknown or unpredictable factors also could affect Aldeyra's results. No forward-looking statements can be guaranteed, and actual results may differ materially from such statements. The information in this presentation is provided only as of January 11, 2022, and Aldeyra undertakes no obligation to update any forward-looking statements contained in this presentation on account of new information, future events, or otherwise, except as required by law.

2

ALDEYRA'S MISSION is to discover and develop innovative medicines that improve the lives of patients that suffer from immune-mediated diseases.

OUR APPROACH is to develop therapies that modulate immunological systems, instead of inhibiting or activating single targets, with the goal of optimizing multiple pathways at once while minimizing toxicity.

3

Aldeyra is a Well-Capitalized Biotechnology Company with a Broad Immunology Pipeline and Near-Term Catalysts

PRODUCT CANDIDATES	DISEASE TARGETS	DEVELOPMENT STAGE	NEXT EXPECTED MILESTONE†
RASP PLATFORM FOR OCULAR AND SYSTEMIC IMMUNE-MEDIATED DISEASES
Reproxalap	Dry Eye Disease	Phase 3	Mid-2022: Final Pivotal Trial Results‡
(ophthalmic solution)	Allergic Conjunctivitis	Phase 3	2023: Final Pivotal Trial Results‡
ADX-629	Psoriasis, Asthma, and COVID-19	Phase 2 Proof-of-Concept	Q1 2022: Data Summary
(oral administration)
RASP-Modulator	Multiple Immune-Mediated	Preclinical	2022: IND Submission
Discovery Platform	Retinal and Systemic Indications
VITREOUS METHOTREXATE PLATFORM FOR RARE RETINAL INFLAMMATORY DISEASES
	Primary Vitreoretinal Lymphoma	Pre-NDA	H2 2022: Regulatory Update
	(U.S. FDA Orphan Drug Designation)
ADX-2191	Proliferative Vitreoretinopathy	Phase 3	H2 2022: Part 1 GUARD Trial Results
(intravitreal injection)	(U.S. FDA Orphan Drug and Fast Track Designation)
	Retinitis Pigmentosa	Phase 2	H2 2022: Trial Results
	(U.S. FDA Orphan Drug Designation)

As of 9/30/2021, cash, cash equivalents, and marketable securities were $241.4M, which is expected to be sufficient to fund operations through the end of 2023, based on projected operating expenses.

† Timing depends, in part, on restrictions related to the COVID-19 pandemic, the availability of clinical research facilities and staffing, the ability to recruit patients, and regulatory feedback.	4
‡NDA submission requirements depend, in part, on clinical results and regulatory feedback. IND = Investigational New Drug. NDA = New Drug Application.

January 2022

REPROXALAP, ADX-629, AND NOVEL RASP MODULATORS

Modulating RASP - A First-in-Class,Systems-Based Therapeutic Approach

Nasdaq: ALDX

© Aldeyra Therapeutics, Inc. 2022